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Mineral or Synthetic


Paul Carrera
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Pauly and Adam,

I am pleased that your mechanics are not your doctors as they would be still using leeches on you!

 

Don't get me wrong, a good mineral oil does the job just as well as a good synthetic but to say that old engines should only use mineral oil has no rational basis. 

 

Ok, I'll bite! Both Porsche and Mercedes (both leaders and at the fore front of automotive design, engineering and manufacture) offer their own oils for older, classic models. These oils are mineral. That is enough for me.

What I do not get is all the snide remarks when someone does not agree with someone else's opinion!

It is after all their opinion. No one is wrong and no one is right. I care not for what anyone else uses, just conveying what one of the foremost Porsche mechanics (from a very large city on the big island and not my mechanic) told me.

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Ok, I'll bite! Both Porsche and Mercedes (both leaders and at the fore front of automotive design, engineering and manufacture) offer their own oils for older, classic models. These oils are mineral. That is enough for me.

What I do not get is all the snide remarks when someone does not agree with someone else's opinion!

It is after all their opinion. No one is wrong and no one is right. I care not for what anyone else uses, just conveying what one of the foremost Porsche mechanics (from a very large city on the big island and not my mechanic) told me.

Err, Porsche doesn't have mineral oils for their classic oil range.

From their documents:

 

 Seal compatibility: 

Modern, high-additive engine oils based on fully synthetic base oils can corrode old sealing materials and make them brittle. There is also a risk that the deposits which have built up in the engine over decades may be dissolved. Both of these processes can result in leaks and, in the worst-case scenario, engine damage. 

Porsche Classic's engine oils are designed to be compatible with materials previously used in Porsche engines, such as leaded bearing shells or cork seals. Both oils have a neutral effect on all such sealing materials. They vastly exceed the performance of simple mineral oils and provide optimum protection for your engine.

and

Mineral oil: 

Oil manufactured by distilling natural crude oil. The process involves the extraction of hydrocarbon molecules in a refinery. The cheap but inexact manufacturing process results in a relatively broad mix of various long-chain hydrocarbons. This has the disadvantage that any unwanted short- or long-chain hydrocarbons have an adverse impact on the behaviour of the oil during operation.

         Porsche Oils - Lexicon       

and 

10W-60 for 911 models with a

displacement of 3.0 litres or

more.

From 3.0-litre engines with drysump

lubrication upwards, the

air-cooled six-cylinder flat

engines of the 911 are suitable

for use with fully synthetic oil and

thus benefit from the advances in

oil development technology.

Porsche Classic

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Adam,

It's not a matter of baiting and biting, I think we are just trying to separate fact from fiction and sometimes beliefs and habits have to be questioned.

I don't intend to cause offense but sometimes information is posted as though it is fact when it is obviously incorrect.  For example your claim above that all the classic oils from Porsche and MB are mineral oils when Taz posted a quote earlier yesterday from Porsche themselves stating their 10w-60 is full synthetic.

I'll admit to being very street driven air cooled 911 "centric" in my oil posts and acknowledge that 928& 944's have specific lubrication issues related to number 2 big end failures occurring as a result  of what appears to me really a combination of oil aeration, crank drilling orientation and bearing shell material issues.  Consequently I do find it hard to accept the proposition that "mineral oils" are "the solution" to an obvious engineering issue. ( If the issue was solely oil related, wouldn't all the big ends fail roughly equally?)

 

As for mechanics, I adore mine but I don't expect just because he works on cars that he is an expert in metallurgy and electronics, let alone oil chemistry and just suggest we should question all advice in hopefully a respectful way.  

 

Edited by Peter M
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Err, Porsche doesn't have mineral oils for their classic oil range.

 

The Porsche Classic 20W-50 is a mineral oil

Adam,

I don't intend to cause offense but sometimes information is posted as though it is fact when it is obviously incorrect.  For example your claim above that all the classic oils from Porsche and MB are mineral oils when Taz posted a quote earlier yesterday from Porsche themselves stating their 10w-60 is full synthetic.

Yes I did see Tazzie's post and I was referring to the 20W 50 oil intended for sub 3.0 litre engines, sorry I should have clarified.

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Ah now I see where the discussion diverted.

Looking at it more, seems like the mineral 20w-50 is for pre 3.0 cars including 356s.  So we should further split this topic by which era your air cooled car comes from.  Clearly the later engines have different sealing materials and closer tolerances and can get benefit from synthetics, but the earlier engines probably don't get any benefit and have the possibility of increased leakage.  It's not a case that all air-cooled engines are the same.

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When I asked, why do manufacturers use synthetic at all; I shouldn't have put a question mark at the end.  It was a rhetorical question; meaning there must be reason.  At the same time I believe different engines, using differing metallurgy are suited to different oils.  

Has as anyone spoke to the mechanics or engine builders at Hamiltons or similar?  I wonder what they think, given they generally only work on P engines.  

As as far as P themselves are concerned, I wonder how many of the older models which will now after 25 plus years be showing wear, they actually inspect? Given they are concentrating on improving and making the next model? Having said that, I understand to improve you need to be aware of previous faults.  Do manufacturers really worry how many km their product can actually do?  So long as it's over 80K, do the really worry? 

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...... At the same time I believe different engines, using differing metallurgy are suited to different oils.  

Norm,

Keen to hear your reasoning but I don't think metallurgy drives oil selection at all.  I think it is more related to bearing clearances, fuel economy requirements for modern cars and cam follower mechanism type that are the main drivers for viscosity and antiwear compounds. 

Has as anyone spoke to the mechanics or engine builders at Hamiltons or similar?  I wonder what they think, given they generally only work on P engines.  

Autohaus use Mobil Super 1000 20w-50 as their standard fill for their G series and early air cooled engines I understand. 

In my search there are few sources of 100% factual information.  Most opinion given is regurgitated internet folk law that doesn't withstand much critical evaluation.    

Edited by Peter M
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You're probably better positioned to know more than me, but aren't bearing clearances related to improved research into metallurgy?  I understand machining has become more accurate also, but both these changes fall in line with my theory that these engineering improvements are also consistent with improvements in oil composition..?

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