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Oil change questions


autojack
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Due to the (extremely frustrating) long delay in getting my new garage built, my 1988 911 has mostly sat for the two years since its last oil change. It has probably been driven a total of five times, for 30--60 minutes at a time, since that change. I'm going to be at the off-site garage where it is stored this weekend, and planning to change the oil. Given how long it has sat, I'm considering just starting it and letting it idle for awhile to warm it up before I drain, or maybe not even bothering with that. I just don't want to go drive it around at all with two-year-old oil in it. Any opinions on this?

Also, I've never thought about this before: the engine oil loop runs up to the front of the car to the oil cooler and back again. When you drain the oil, is that whole loop going to be drained as well? Or is there always some residual oil left in there? Seems like it could be a liter or more. Just curious.

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Best to start the car and drive it, having it sit idle is not a good way of warming cars up.

Warm engines have thinner oil which makes more of it drain, I usually drain for 60minutes on a flat surface.

Always use new sump washer and clean filter. Although it has been parked up, I suggest you get oil analysis done via Caterpillar or similar, cost is $30 and in 5 days you know what is worn and if any water/condensation etc is in oil. I do this prior to oil change as I only drive 1500kms/year and hence if oil is as new, why change it especially if the 5/40 is not worn down and no heavy metals found and or water in oil due to contamination or condensation which happens in hot/cold climates and if engine never gets to full operating temperatures.

Happy to post a oil analysis if interested and info on how to interpret it.

Best oil after much research is also AMSOIL, lots of research done on that via Youtube by labs all around the world. Just saying and do not want to start a oil discussion.

Good luck

 

 

 

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5 hours ago, autojack said:

 

Also, I've never thought about this before: the engine oil loop runs up to the front of the car to the oil cooler and back again. When you drain the oil, is that whole loop going to be drained as well? Or is there always some residual oil left in there? Seems like it could be a liter or more. Just curious.

Used to think the same thing when changing the oil in the 964, Until Criss from Weissach sport showed me how to clear the lines and coollers with low air pressure, but sorry can not remember :(

N

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7 hours ago, autojack said:

Due to the (extremely frustrating) long delay in getting my new garage built, my 1988 911 has mostly sat for the two years since its last oil change. It has probably been driven a total of five times, for 30--60 minutes at a time, since that change. I'm going to be at the off-site garage where it is stored this weekend, and planning to change the oil. Given how long it has sat, I'm considering just starting it and letting it idle for awhile to warm it up before I drain, or maybe not even bothering with that. I just don't want to go drive it around at all with two-year-old oil in it. Any opinions on this?

Also, I've never thought about this before: the engine oil loop runs up to the front of the car to the oil cooler and back again. When you drain the oil, is that whole loop going to be drained as well? Or is there always some residual oil left in there? Seems like it could be a litre or more. Just curious.

I think you are worrying needlessly.

The current engine oil will most likely return "like new" results in an Used Oil Analysis with negligible contaminates and significant remaining life because you have allowed it to reach normal operating temperature on the rare occasions you have started the engine.  (I'm assuming you have effective air filtration, haven't been driving on dusty roads with no filtration or an unmaintained K&N filter and the engine and oil tank haven't been exposed to the elements or pressure washing.)

You need to remind yourself that we do annual oil changes on these cars because that's the habit and is what the future purchasers of classic cars expect to see, not because the oil is no longer effective or somehow bad.  Sure, engine oil is cheap compared to engine rebuilds but I think you are nowhere near this condition.

As for the oil cooler lines, they contain about 3 litres which doesn't drain out when you remove the sump plugs.  Like Tomo said, it can be blown out with air pressure but very people bother as there is no tangible benefit normally.

I suggest you carry out an oil change just like you normally do without special consideration.

If you want to worry about anything, just make sure you do not allow any contaminates - dirt and lint - into the oil tank as this oil goes directly to the oil pump and engine bearings and only gets filtered on the return to the tank on these pre-964 cars. 

  

 

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Thanks for the replies :) I always did think that if the oil is just sitting the car while it's parked, barring unusual conditions or problems, it should be little different from sitting in the jug on the store shelf. But after doing some reading I got spooked with talk of condensation/moisture build-up, corrosion, and all manner of other terrible things that could be happening while the car is just sitting. Scarier than a huntsman down the back of your shirt! I wasn't really worried about the oil in the cooler lines, more just curious about how it is plumbed. I read elsewhere that until the thermostat opens up at temperature, nothing will flow in or out of that loop. But the after-market oil coolers made by Elephant Racing apparently have a drain on them for this reason, for the truly anal or fearful :D 

I'll take it for a leisurely drive, do the change, and leave my worries behind.

The garage build at home is getting rolling now and should be done in June, after which I've promised my kids a weekly ride to school in the Porsche :) 

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On 09/03/2022 at 21:56, autojack said:

Thanks for the replies :) I always did think that if the oil is just sitting the car while it's parked, barring unusual conditions or problems, it should be little different from sitting in the jug on the store shelf. But after doing some reading I got spooked with talk of condensation/moisture build-up, corrosion, and all manner of other terrible things that could be happening while the car is just sitting. Scarier than a huntsman down the back of your shirt! I wasn't really worried about the oil in the cooler lines, more just curious about how it is plumbed. I read elsewhere that until the thermostat opens up at temperature, nothing will flow in or out of that loop. But the after-market oil coolers made by Elephant Racing apparently have a drain on them for this reason, for the truly anal or fearful :D 

I'll take it for a leisurely drive, do the change, and leave my worries behind.

The garage build at home is getting rolling now and should be done in June, after which I've promised my kids a weekly ride to school in the Porsche :) 

To be honest, I think if you did an oil analysis you'd find that you wouldn't even need to bother changing it. You've got it upto temp every time you've driven it, which helps reduce condensation. Out of curiosity, I'd do an oil analysis, just to see. You'd get away with another year, or two I'd say at the minimum with those kms. 

We aren't using Dinosaur oils anymore, most are using synthetics, which take alot longer to degrade and contaminate. 

I'd say under 2,500 kms annually, an oil change at 2 year intervals is fine, providing you get it up to temp every time you drive.

Relax and drive the car. 

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