911 Engine oil preference

[TINGY]

Here we go again

[Peter M]

Repco have 40% off all store stock Shell and Valvoline oil this weekend only.

[Coastr]

Repco have 40% off all store stock Shell and Valvoline oil this weekend only.

And a trolley jack for ten bucks if you spend $100

Whats the best choice of the on-special oils to buy?

[Peter M]

 

And a trolley jack for ten bucks if you spend $100

Whats the best choice of the on-special oils to buy?

I've got one of those jacks and it works fine.  However it is too high to fit under the front and I have to use my heavy low profile trolley jack for that.  But I do use it often as it is light weight and easy to manoeuvre.  10 bucks is a bargain!

Best choice oil?

My conclusion after a year of study is to pick any global brand with A3/B4 classification in any half sensible viscosity grade and you can't go wrong.  Placing any more effort into the selection and you are frankly splitting hairs based a whim rather than anything that can be statistically validated.

Edited 8August, 2015 by Peter M

[tazzieman]

My conclusion after a year of study 

I anoint you the resident PFA oleologist!

B.O.

[Coastr]

Well I got three containers of helix for about $40ea, and threw in a trolley jack for $10.

 

all told, saved $150 over full retail.  I think women call that investment shopping or something.

[Peter M]

I humbly submit my thesis:

Porsche 911 Air Cooled Engine Oil

 

I’ve been searching for the best engine oil for my 911’s for over a year now.  After trawling forums seeking the truth, even a couple of manufacturer and SAE papers for good measure, there seems to be five distinct points of view:

 

Thick and ZDDP is Best – This enclave sees engine oil as simply a combination of viscosity and zinc based anti-wear additives and are happiest with either a 20W-50 or a 10W-60 and an absolute minimum ZDDP content of 1200ppm.  Most likely encountered on American forums where they use fear as their best tool of persuasion and reference the destruction of “flat tappets” engines as solely related to “thin oils” and the reduction of ZDDP in the ILAC requirements and infer this is the reason some 911 engines pit their cam lobes.  The fact that ILAC requirements only affect Xw-30 and under viscosity grades doesn’t seem to register

 

Generally there is no reference to API, let alone ACEA or any of the manufacturer oil approvals.  They think HTHS is a kind of long lasting milk and also love antidotes about the failure of particular engines that someone who knew someone else’s friend had because the oil was “to thin”.  I reckon it would be great to be a member of this group as life is simple as everything is black or white with no room or need for grey here.

 

Favourite oils are Valvoline VR 20w-50, Brad Penn 20w-50 and Mobil 1 Vee Twin 20w-50 and they will go to extraordinary lengths to obtain these brands due to the mythical attributes these oils bring to their engines.   Penrite HPR30 is also a favourite brew locally.

 

Mixed Fleeters – This group has largely developed from the stories of success that engine builders of using “diesel” engine oil to make their flat tappet cam lobes last in American V8’s in the late 80’s and 90’s.  Whilst the real reason for the lobe wear was probably related to the turmoil in the American auto industry at the time and the outsourcing of many engine parts to cheaper, usually foreign providers, this group identified that mixed fleet engine oil is cheap, of consistently high standard, subject to more controlled testing that any other engine oil due to the widespread fleet usage and importantly, the API classifications of CI and CI Plus contain around 1500ppm of zinc compounds and other anti-wear additives

 

In many ways the use of mixed fleet oil in 911’s should not be a surprised as Porsche themselves used these oils as first fill for much of the ’60’s for many of the reasons stated above.

 

Whilst the mixed fleet oils are widely acclaimed by all, the viscosities are generally restricted to 15w-40’s making them not thick enough for the “Thick is Best” group and too thick cold for our next faction, the “Euro oilers” below.

 

Favourite oils are the API CI and CI Plus classified Mobil MX 15w-40, all the Shell Rimula’s and Caltex Delo’s.  However the later CJ classified oils have also proven very effective even with the reduced SAPS and by definition zinc content.

 

Euro Oils – This group are enthusiastic users and have posters of Mobil 1 0w-40 adverts on their bedroom walls, talk at length in tedious code about ACEA, A40, MB 229.5 and know their air cooled 911’s have never had “flat tappets” cam followers.  They also realise that the pitting of cam lobes is primarily due to corrosion and will happily point you to a Google search of Lycoming aircraft engines to support their beliefs.

 

This group is prone to carry our used oil analysis, antagonise the “Thick is Best” flat earthers when it’s reasonably safe to do so on forums.  However the sheer numbers of “Thick is Best” mob usually drives back any incursions pretty quickly.  Their worst habit, besides being a little to smug, is to bang on about how the low temperature viscosity of their oils protects their engines on start- up not realising that any vaguely suitable oil pumps at the same speed irrespective of viscosity due to our oil pumps being positive displacement. (Also has any one disassembled an old engine that had completely dry bearings, even 12 months after it was last run?)

 

They acknowledge that ZDDP is a cornerstone anti wear compound and are satisfied that their preferred brews contain around 1100ppm.  They are also quick to point out that there are many more modern anti-wear compounds that can’t be detected in a simple $35 oil analysis kit that only major oil companies can develop and this is what makes these oils unbeatable.

 

Favourite oils are Mobil 1 0w-40 if they can afford the cost and Shell Ultra 5w-40 for those hard up.

 

Porsche Classic Oils – This group has been recently created by the Porsche Classic marketing department to exploit those 911 owners that suffer engine oil related anxiety, have money in their pockets and like the novelty of a specially illustrated tin container.  Their Youtube video illustrates this marketing approach by devoting the majority of the video to the development of the tin rather than the contents.  Porsche Classic decided to offer a 20w-50 and a 10w-60 as they thought that’s what their market segment were expecting to see.

 

The 20w-50 has been independently tested at less than 900ppm of zinc and both oils do not have any API or ACEA certification as it is a manufacturer supplied oil.  I still haven’t figured out why Porsche doesn’t see the inconsistency of this approach with their A40 oil approval scheme that they also recommend for any post 1984 car. 

 

Nothing makes this group prouder than displaying their fancy oil tins in the “man cave”.

 

The Non Forum User – Surely the most common user group that is happy to use any quality oil that meets the API classification and viscosity specified in their car’s Driver’s Manual.  They even don’t know what a sliding finger follower is and are happily unaware that their engine has 8 of them.  However it is clear that lubrication systems of these air cooled engines are robust and the use of oils that comply with the Driver’s Manual and replaced regularly does lead to a long engine life.

 

 

 

So what is the best oil?

 

No one will ever know!  In fact there is no statistically valid evidence to support any of the above will lead to a better longer lasting engine than the other.  What is more important is:

 

Effective air cleaner – Chuck that K&N to the shit house and replace with an OEM style paper filter and check all the ducting is leak free.

 

Warm Up the Engine Before Trashing – Drive off as soon as you can and allow the engine to warm up gently to the first notch before putting your foot in it.

 

Limit Your Short Trips – but drive regularly to keep internal corrosion at bay.

 

Keep the Oil Tank Clean – A quirk of the pre 964 engines is that the oil pumped from the external tank is not filtered before it reaches the bearings so just remind yourself to use a clean funnel and clean, preferably paper towelling to wipe the dip stick when topping up.

 

Relax – Remind yourself “It doesn’t matter!” as you won’t live long enough to find out.

 

Edited 10November, 2015 by Peter M
usaly speling. Included HPR30 reference

[StevepGT3]

I humbly submit my thesis:

Porsche 911 Air Cooled Engine Oil

 

I’ve been searching for the best engine oil for my 911’s for over a year now.  After trolling forums seeking the truth, even a couple of manufacturer and SAE papers for good measure, there seems to be five distinct points of view:

 

Thick and ZDDP is Best – This enclave sees engine oil as simply a combination of viscosity and zinc based anti-wear additives and are happiest with either a 20W-50 or a 10W-60 and an absolute minimum ZDDP content of 1200ppm.  Most likely encountered on American forums where they use fear as their best tool of persuasion and reference the destruction of “flat tappets” engines as solely related to “thin oils” and the reduction of ZDDP in the ILAC requirements and infer this is the reason some 911 engines pit their cam lobes.  The fact that ILAC requirements only affect Xw-30 and under viscosity grades doesn’t seem to register

 

Generally there is no reference to API, let alone ACEA or any of the manufacture oil approvals.  They think HTHS is a kind of long lasting milk and also love antidotes about the failure of particular engines that someone who knew someone else’s friend had because the oil was “to thin”.  I reckon it would be great to be a member of this group as life is simple as everything is black or white with no room or need for grey here.

 

Favourite oils are Valvoline VR 20w-50, Brad Penn 20w-50 and Mobil 1 Vee Twin 20w-50 and they will go to extraordinary lengths to obtain these brands due to the mythical attributes these oils bring to their engines.

 

Mixed Fleeters – This group has largely developed from the stories of success that engine builders of using “diesel” engine oil to make their flat tappet cam lobes last in American V8’s in the late 80’s and 90’s.  Whilst the real reason for the lobe wear was probably related to the turmoil in the American auto industry at the time and the outsourcing of many engine parts to cheaper, usually foreign providers, this group identified that mixed fleet engine oil has cheap, consistently high standard, subject to more controlled testing that any other engine oil due to the widespread fleet usage and importantly the API classifications of CI and CI Plus contained around 1500ppm of zinc compounds and other anti-wear additives

 

In many ways the use of mixed fleet oil in 911’s should not be a surprised as Porsche themselves used these oils as first fill for much of the ’60’s for many of the reasons stated above.

 

Whilst the mixed fleet oils are widely acclaimed by all, the viscosities are generally restricted to 15w-40’s making them not thick enough for the “Thick is Best” group and too thick cold for our next faction, the “Euro oilers” below.

 

Favourite oils are the API CI and CI Plus classified Mobil MX 15w-40, all the Shell Rimula’s and Caltex Delo’s.  However the later CJ classified oils have also proven very effective even with the reduced SAPS and by definition zinc content.

 

Euro Oils – This group are enthusiastic users and have posters of Mobil 1 0w-40 adverts on their bedroom walls, talk at length in tedious code about ACEA, A40, MB 229.5 and know their air cooled 911’s have never had “flat tappets” cam followers.  They also realise that the pitting of cam lobes is primarily due to corrosion and will happily point you to a Google search of Lycoming aircraft engines to support their beliefs.

 

This group is prone to carry our used oil analysis, antagonise the “Thick is Best” flat earthers when it’s reasonably safe to do so on forums.  However the sheer numbers of “Thick is Best” mob usually drives back any incursions pretty quickly.  Their worst habit, besides being a little to smug, is to bang on about how the low temperature viscosity of their oils protects their engines on start- up not realising that any vaguely suitable oil pumps at the same speed irrespective of viscosity due to our oil pumps being positive displacement. (Also has any one disassembled an old engine that had completely dry bearings, even 12 months after it was last run?)

 

They acknowledge that ZDDP is a cornerstone anti wear compound and are satisfied that their preferred brews contain around 1100ppm.  They are also quick to point out that there are many more modern anti-wear compounds that can’t be detected in a simple $35 oil analysis kit that only major oil companies can develop and this is what makes these oils unbeatable.

 

Favourite oils are Mobil 1 0w-40 if they can afford the cost and Shell Ultra 5w-40 for those hard up.

 

Porsche Classic Oils – This group has been recently created by the Porsche Classic marketing department to exploit those 911 owners that suffer engine oil related anxiety, have money in their pockets and like the novelty of a specially illustrated tin container.  Their Youtube video illustrates this marketing approach by devoting the majority of the video to the development of the tin rather than the contents.  Porsche Classic decided to offer a 20w-50 and a 10w-60 as they thought that’s what their market segment were expecting to see.

 

The 20w-50 has been independently tested at less than 900ppm of zinc and both oils do not have any API or ACEA certification as it is a manufacturer supplied oil.  I still haven’t figured out why Porsche doesn’t see the inconsistency of this approach with their A40 oil approval scheme that they also recommend for any post 1984 car. 

 

Nothing makes this group prouder than displaying their fancy oil tins in the “man cave”.

 

The Non Forum User – Surely the most common user group that is happy to use any quality oil that meets the API classification and viscosity specified in their car’s Driver’s Manual.  They even don’t know what a sliding finger follower is and are happily unaware that their engine has 8 of them.  However it is clear that lubrication systems of these air cooled engines are robust and the use of oils that comply with the Driver’s Manual and replaced regularly does lead to a long engine life.

 

 

 

So what is the best oil?

 

No one will ever know!  In fact there is no statistically valid evidence to support any of the above will lead to a better longer lasting engine than the other.  What is more important is:

 

Effective air cleaner – Chuck that K&N to the shit house and replace with an OEM style paper filter and check all the ducting is leak free.

 

Warm Up the Engine Before Trashing – Drive off as soon as you can and allow the engine to warm up gently to the first notch before putting your foot in it.

 

Limit Your Short Trips – but drive regularly to keep internal corrosion at bay.

 

Keep the Oil Tank Clean – A quirk of the pre 964 engines is that the oil pumped from the external tank is not filtered before it reaches the bearings so just remind yourself to use a clean funnel and clean, preferably paper towelling to wipe the dip stick when topping up.

 

Relax – Remind yourself “It doesn’t matter!” as you won’t live long enough to find

 now you have finished with oil, please work on how to understand women and you will get my vote for life membership

 

[Coastr]

now you have finished with oil, please work on how to understand women and you will get my vote for life membership

Always use a lint-free cloth and keep your dipstick clean

[LeeM]

I like the term 'investment shopping' personally.

Will have to remember that one

[Russ]

Warm Up the Engine Before Trashing

I don't set out to kill my engine every time!

Edited 10August, 2015 by Russ

[JV911]

I'm using Mobil Super 1000 20w-50 Multigrade in the 964 as advised by Autohaus. 3,500km so far

Was told in no uncertain terms not to use semi or full synthetic.

[Peter M]

I used to use Mobil Super 1000 20w-50 Multigrade in my C3.2 as supplied by Autohaus.  I've since found better oils.

[ByronBayChris]

Mine has Mobil 2000 10/50, which I will now be discussing with Mr mechanic.   Appears one of the worse ones? 

[JV911]

I've since found better oils.

better in what way?

[Peter M]

Oil Consumption Update
 
Until September last year I was using Mobil Super X2 1000 20W-50 in my Carrera 3.2 as it is the default fill at one of the big independent workshops in Sydney and I know many other owners use it too.

http://www.mobil.com/AP-English-LCW/carengineoils_au_products_mobil-super-1000-x2-20w50.aspx#

After a bit of head scratching and my belief at the time that I really needed a high ZDDP oil I changed to a well regarded mix fleet oil Caltex Delo 400 15W-40.

http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB0QFjAA&url=http%3A%2F%2Fwww.caltex.com.au%2FFPL%2520PDS%2FDelo%2520400%2520Multigrade.pdf&ei=CSAfVZ-GCsK3mAXZ34G4Dg&usg=AFQjCNEpoPcNxzjYnsNk-B23QS0Ir9t5Kw

I expected the oil consumption to remain similar or even increase slightly given the lower viscosity grade but have found the opposite to be true. Over the last 3621km it is averaging just over 70ml/1000km which is less than half it was using previously and especially remarkable when Porsche's upper consumption limit for these engines is 1500ml/1000km.

 

For my next change due in September I'll just heed my own A3/B4 advice above.

 

better in what way?

Jay,

I found in practice that my C3.2 consumed significantly more that the current oil fill.

It's a low cost, mid SAPS oil that has minimal certifications.  Certainly fine from a HTHS point of view and obviously Autohaus's previous experience.  Just think know there are better choices available.  But as I've said before, probably splitting hairs!    

[JV911]

does lower consumption mean it's better though (genuine question) or are you looking at the ZDDP content?

[Peter M]

Originally I was attracted to the higher ZDDP and lower start up viscosity.  The unexpected dramatic reduction in consumption was a pleasant surprise along with the more willing, smoother feel of the engine when it is cold.

The lower consumption is probably the result of the oil having lower volatility as commonly measured by the NOACK test.  Generally the higher quality oils have a NOACK result of well less than 10%.

As I've posted earlier this week, there are many options when it comes to engine oil and my view is to just select the one that appeals to you.  I've just happen to find I like high quality (as measured by the various certifications), global brand  Xw-40 viscosity grades.  After using 20w-50 for 30 years, this is only a recently developed habit.  Others make different choices and that's equally valid.

But like I have said before, we are in the splitting hairs zone of oil nerdism so lets keep all this in prospective.

It would be interesting to hear the mechanics reasoning in your case but I suspect it related to you having a freshly rebuild engine and they are worried about the rings seating and just maybe, the exaggerated correlation with oil leaks that synthetics used to have.  However what they are suggesting is a safe choice and you have nothing to worry about.

[Peter M]

 

Bhaaaaaa!  Why's it quoting weirdly?!!

 

Chris,

That oil looks OK to me and I wouldn't lose any sleep about using it.

http://www.mobil.com/AP-English-LCW/carengineoils_au_products_mobil-super-2000-x2-10w40.aspx#

Edited 14August, 2015 by Peter M

[tazzieman]

I’ve been searching for the best engine oil for my 911’s for over a year now.  After trolling forums

Trawling,  I hope. 

We frown upon trolling at PFA 

[CarreraG50]

Got bored half way through but if you want to persevere-:

'Synthetic' as the word relates to motor oil

Monday, November 2, 2015

By Michael Trueba, Jr.
Images courtesy MPT Industries

MPT Industries’ Michael Trueba, Jr. realizes that synthetic oil is a confusing hot-button topic, and knowledge of what is really contained in the quart-sized bottles labeled “Synthetic” is hard to come by. In this article, he defines synthetic as it pertains to contemporary motor oil and explains why the definition is so broad; outlines the various qualities of conventional, partial-synthetic, and full-synthetic motor oils; and recommends two widely accepted test procedures that are worth your consideration when shopping for motor oil.

So you just purchased a case of what you believe to be high-quality synthetic motor oil from your local auto parts store or online retailer. How much of it is really the high-quality synthetic you think you bought? Although the majority of the big-name manufacturers offer them, it is widely accepted among industry experts that oils labeled “synthetic” are not equal, and some are not fully synthetic.

Let’s start our analysis with some background on the current, loose definition of synthetic oil, which is, an oil containing base stock that was synthesized through an intended chemical reaction. Crucially, there are no federal guidelines for using the word synthetic in the sale and distribution of motor oil in the U.S. As a result, the current definition stems from a complaint brought before the Better Business Bureau‘s National Advertising Division (NAD) on March 1, 1999 by Mobil regarding Castrol Syntec motor oil.

At the time, Mobil 1 was comprised of polyalphaolefin (PAO) base stocks, chemically synthesized from ethylene. Its complaint was centered on the fact that Castrol Syntec — comprised of hydrocracked or wax isomerized petroleum base stocks, or highly refined crude oil — was labeled and marketed as synthetic. In brief, the NAD ruled that the performance characteristics of Castrol Syntec and Mobil 1 were remarkably similar, and Syntec’s base stock was in fact synthesized from crude oil because it had an unnatural molecular arrangement that was a product of an “intended chemical reaction.”

This has allowed a broad interpretation of what is synthetic oil that runs contrary to what many oil experts now often label “true synthetic”— which includes oils that contain PAO, polyalkylene glycol, and/or esters as base stocks. The decision has also made the term synthetic less useful in determining oil quality. Established guidelines amongst major players such as Mobil and Castrol are the most widely accepted standards, however, some manufacturers and marketers also view the NAD’s decision increasingly as an open door to use cheaper, lower quality petroleum base stocks in formulating their synthetic motor oils. To compound this problem, many manufacturers will now blend synthetic with non-synthetic base stocks, lowering the bar even more as to what can be called synthetic.

A basic primer on lubricant base stocks reveals the five API categories that cover all conventional and synthetic oils. They are indispensible tools for understanding what is in oil and which type of oil is best suited for certain applications.

API motor oil categories and what they mean

Group I — Solvent-refined crude oil. High wax and aromatic (organic matter) content. Used in low-grade conventional motor oils.

Group II — Hydrotreated crude oil refining process. Less wax and aromatic content. Used in themajority of conventional motor oils.

Group III — Wax isomerized or hydrocracked crude oil refining process. Group III base stocks are considered synthetic because their molecular structures are altered through an intended chemical reaction. Very low wax and aromatic content. Used in the majority of synthetic motor oils.

Group IV — Polyalphaolefin (PAO) base stocks are chemically synthesized from ethylene. Used in some synthetic motor oils.

Group V — All other chemically synthesized base stocks, including all esters and polyalkylene glycol (PAG). Used in the minority of synthetic motor oils.

Though they have similar performance characteristics, should you be concerned about the substitution of Group IV or V with Group III base stocks in your synthetic motor oils? Your application, maintenance schedule, and the targeted price point will determine the answer. 

Full synthetic motor oils manufactured by the major brands and sold by the leading automotive chain stores are comprised of primarily Group III base stocks. Although some may also contain small amounts of Group II base stocks, they are good-quality motor oils with American Petroleum Institute (API) approvals that you can confidently put in your crankcase knowing they meet the requirements of new-car manufacturers.

However, by no means are Group III synthetic motor oils of the highest quality or necessarily the best product for your application. Pricing and affordability will be determining factors, as well as driving environment and intended use of your vehicle. A Group III-based full synthetic motor oil on sale at the local mega-store may be the best value if your requirements are ordinary, such as city or highway driving, the occasional autocross, and back road driving. But if vehicle use and ambient conditions will be more demanding, including high-performance driving, high heat or extreme cold, frequent short trips, longer oil change intervals, etc., a motor oil with Group IV or V base stocks may be for you.

Generally, Group IV and V base stocks, such as polyalphaolefins, esters, or polyalkylene glycols, will have performance advantages over Group III base stocks regardless of how well refined they may be. These advantages include a lower pour point (temperature at which the oil becomes semi-solid), less volatility or lubricant evaporation due to temperature, and better shear protection (more resistant to physical breakdown). Most formulators of high-performance synthetic oil will blend a variety of Group IV and V base stocks, which can help build a type of synergy between them. They also are often blended with Group III base stocks to help control the price and aid with the solubility issues sometimes associated with certain types of Group IV and V base stocks.

How to pick the correct oil for your application

Regardless of the type, synthetic base stocks normally make up about 70-85% of the overall oil content. The rest includes viscosity modifiers, friction modifiers, anti-wear agents, anti-foaming agents, corrosion inhibitors, dispersants, and other anti-oxidants to keep it from degrading over time.

Unfortunately, manufacturers and marketers of synthetic motor oils can be less than forthcoming with information regarding the types of base stocks and additives used in their product formulas. As a result, the only way to determine their quality and effectiveness is through a series of American Society of Testing Materials (ASTM) tests. For example, the Noack volatility test (ASTM D5800) measures the evaporation loss at high temperature. Another favorite is the High Temperature/High Shear (HTHS) test (ASTM D5481), which measures the viscosity of motor oil under high temperature and shear conditions. 

These tests are reliable indicators of the type and the quality of base stocks used in any motor oil. Unlike more traditional tests, such as viscosity index and flash point, which can be altered through the use of viscosity modifiers and other additives (short term modifications that show their weaknesses under performance testing), the Noack volatility and HTHS tests show the true capability or weakness of the base stocks when it is most important: under stressful, high-heat conditions. Obtaining the information may be difficult, however, since companies often do not publish all relevant testing information on their websites — sometimes none at all — and most consumers consider the tests to be prohibitively expensive to perform independently.

If you feel Group IV or V synthetic base stocks are important for your application, it is recommended that you do some research prior to shopping. Check oil manufacturers’ websites or company information for test data. (See sidebar below to find out how to look for and analyze these tests.) Motor oils that are comprised of Group IV synthetic base stocks generally have very low evaporation loss numbers and high numbers for shear testing. If this information is not readily available, email or phone the manufacturers. If they will not offer test results, it may mean that it is not in their best interest to do so.

Analyzing motor oil test results How does one identify and analyze test results when they may not be publicly available? It can be difficult, but keep in mind that companies often encourage the use of test methods in which their products perform best. Amsoil, for example, blends a high percentage of Group IV base stocks into its top-tier motor oils, so it behooves the company to promote the Noack and HTHS tests because they favor motor oils that have high percentages of Group IV and V base stocks. The same goes for MPT Industries’ top-tier motor oils, which contain a mix of Group IV and V base stocks to attain the desired viscosity range without using viscosity modifiers. Motor oils with Group I, II, or III base stocks will not perform as well, and therefore Noack and HTHS tests are often not published for them. Most motor oils sold in the auto parts stores are approved by the American Petroleum Institute (API), which means they must meet certain standards. In the case of the Noack test, the maximum percentage allowed for API approval is 15%. The lower the test number, the less lubricant will be lost due to evaporation. It is worth noting that evaporation loss decreases as the viscosity of the motor oil increases. For example, Noack test results will generally be much higher with a 0W20 motor oil than a 20W50 motor oil. The best way to determine how good or bad a given Noack number is would be to compare it with some other competing brands in the same viscosity range (the same is true for HTHS). High Temperature/High Shear testing is also a difficult test method that exhibits how well motor oil performs under high heat and high shear conditions. Motor oils that maintain their viscosity for longer periods perform better in this test. (Viscosity is measured in centistokes.) Once again, higher viscosity motor oils will tend to naturally outperform those with lower viscosity. For example, a 0W20 will not maintain its intended viscosity as long as a 20W50.

 

[tazzieman]

"Right"

[Coastr]

Well, if you go back a few pages you'll see I bought some shell helix 10w-40 synthetic.   I did a few hundred miles but didn't like it.  It constantly gave lower oil pressure thank was used to, especially at hot idle.  Ok so I didn't have scientific recording method but I usually got 1 bar per thousand revs and another half a bar on that at an oil temp of around 90 degrees.  I was getting just short of 1 bar with the synthetic.

plus I did some more reading on sn/cf formulas and the change for emissions coupled with the change in engine construction that accompanied them.  All these things ate away at my thoughts until I realised I was even thinking about this - for what end?  So I could say I used synthetic?

so I dumped the synthetic and replaced it with some mineral 20w/50, essentially pouring 10 litres of lightly used synthetic down the drain (did not actually use drain!) There was probably nothing wrong with the synthetic at all.  But if you're driving along second guessing something, that takes away from the enjoyment.

so my advice is to do what is technically within parameters but also what makes you feel comfortable.  Apparently for me that is mineral oil and I'm apparently one of those thicker is better crowd.

Anyway it was a hot day today and while stuck in traffic the oil temp climbed to about 120, and even then I was still getting just short of 1 bar of druck at idle.

So I felt much better even though I know that is irrational.

[michel]

[Peter M]

The Dunning–Kruger effect is a cognitive bias wherein relatively unskilled individuals suffer from illusory superiority, mistakenly assessing their ability to be much higher than is accurate. Dunning and Kruger attributed this bias to a metacognitive inability of the unskilled to recognize their own ineptitude and evaluate their own ability accurately. Their research also suggests corollaries: highly skilled individuals may underestimate their relative competence, they may erroneously assume that tasks which are easy for them are also easy for others, and they may incorrectly suppose that their competence in a particular field extends to other fields in which they are less competent.^[1] The bias was first experimentally observed by David Dunning and Justin Kruger of Cornell University in 1999.

Dunning and Kruger have postulated that the effect is the result of internal illusion in the unskilled, and external misperception in the skilled: "The miscalibration of the incompetent stems from an error about the self, whereas the miscalibration of the highly competent stems from an error about others."

Original Study

The phenomenon was first tested in a series of experiments during 1999 by David Dunning and Justin Kruger of the department of psychology at Cornell University.^[1][2] The study was inspired by the case of McArthur Wheeler, a man who robbed two banks after covering his face with lemon juice in the mistaken belief that, because lemon juice is usable as invisible ink, it would prevent his face from being recorded on surveillance cameras.^[3] The authors noted that earlier studies suggested that ignorance of standards of performance lies behind a great deal of incorrect self-assessment of competence. This pattern was seen in studies of skills as diverse as reading comprehension, operating a motor vehicle, and playing games such as chess or tennis.

Dunning and Kruger proposed that, for a given skill, incompetent people will:^[4]

• fail to recognize their own lack of skill
• fail to recognize genuine skill in others
• fail to recognize the extent of their inadequacy
• recognize and acknowledge their own lack of skill, after they are exposed to training for that skill

Dunning has since drawn an analogy – "the anosognosia of everyday life"^[5][6] – with a condition in which a person who experiences a physical disability because of brain injury seems unaware of, or denies the existence of, the disability, even for dramatic impairments such as blindness or paralysis: "If you're incompetent, you can’t know you’re incompetent.… [T]he skills you need to produce a right answer are exactly the skills you need to recognize what a right answer is."^[5]

Supporting studies

Dunning and Kruger set out to test these hypotheses on Cornell undergraduates in psychology courses. In a series of studies, they examined subject self-assessment of logical reasoning skills, grammatical skills, and humor. After being shown their test scores, the subjects were asked to estimate their own rank. The competent group estimated their rank accurately, while the incompetent group overestimated theirs. As Dunning and Kruger noted:

Across four studies, the authors found that participants scoring in the bottom quartile on tests of humor, grammar, and logic grossly overestimated their test performance and ability. Although test scores put them in the 12th percentile, they estimated themselves to be in the 62nd.^[1]

Meanwhile, subjects with true ability tended to underestimate their relative competence. Roughly, participants who found tasks to be easy, erroneously presumed to some extent, that the tasks also must be easy for others.^[1]

A follow-up study, reported in the same paper, suggests that grossly incompetent students improved their ability to estimate their rank after minimal tutoring in the skills they had previously lacked, regardless of the negligible improvement gained in skills.^[1]

In 2003, Dunning and Joyce Ehrlinger, also of Cornell University, published a study that detailed a shift in people's views of themselves when influenced by external cues. Participants in the study, Cornell University undergraduates, were given tests of their knowledge of geography. Some of the tests were intended to affect their self-views positively, some negatively. They were then asked to rate their performance. Those given the positive tests reported significantly better performance than those given the negative.^[7]

Daniel Ames and Lara Kammrath extended this work to sensitivity to others and subject perception of how sensitive they were.^[8]

Research conducted by Burson et al. (2006) set out to test one of the core hypotheses put forth by Kruger and Muller in their paper "Unskilled, unaware, or both? The better-than-average heuristic and statistical regression predict errors in estimates of own performance", "that people at all performance levels are equally poor at estimating their relative performance".^[9] To test this hypothesis, the authors investigated three different studies, which all manipulated the "perceived difficulty of the tasks and hence participants’ beliefs about their relative standing".^[9] The authors found that when researchers presented subjects with moderately difficult tasks, the best and the worst performers varied little in their ability to accurately predict their performance. Additionally, they found that with more difficult tasks, the best performers were less accurate in predicting their performance than the worst performers. The authors concluded that these findings suggest that "judges at all skill levels are subject to similar degrees of error".^[9]

Ehrlinger et al. (2008) made an attempt to test alternative explanations, but came to conclusions that were qualitatively similar to the original work. The paper concludes that the root cause is that, in contrast to high performers, "poor performers do not learn from feedback suggesting a need to improve".^[10]

Studies on the Dunning–Kruger effect tend to focus on American test subjects. A number of studies on East Asian subjects suggest that different social forces are at play in different cultures. For example, East Asians tend to underestimate their abilities and see underachievement as a chance to improve themselves and to get along with others.^[11]

Historical antecedents

Although the Dunning–Kruger effect was formulated in 1999, Dunning and Kruger have noted earlier observations along similar lines by philosophers and scientists, including Confucius ("Real knowledge is to know the extent of one's ignorance"),^[2]Bertrand Russell ("One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision"),^[10] and Charles Darwin, whom they quoted in their original paper ("Ignorance more frequently begets confidence than does knowledge").^[1]

Geraint Fuller, commenting on the paper, noted that Shakespeare expressed a similar observation in As You Like It ("The Foole doth thinke he is wise, but the wiseman knowes himselfe to be a Foole" (V.i)).^[

 

Edited 21November, 2015 by Peter M