burning oil

[C50]

i can smell burning oil in my 944S, and not sure if it's because im running on Mobil Super S 10w40. I don't see any smoke but she does drink oil. Is this normal on a 944? I'm deciding whether i should put back in 15w40 which it has always run on from the service history [&:]

 

[zcacogp]

Changing thick oil to thin oil can cause problems. Why did you make the switch to 10w40? Are you sure it is burning and not leaking? A small amount of oil burned makes a huge amount of blue smoke - if the car is drinking it and only burning then it will live in a constant blue cloud. Oli.

 

[C50]

no smoke. But it does drink oil though. [&:] i put in the thinner stuff as i thought it would give it better cold start circulation (i know its summer) but the viscosity should still the same when warmed up.

 

[Northern924]

True enough, in a new car, but don't forget you are running a car that is over 20 years old, if anything you should be looking at a thicker oil with additives specially added for older/higehr milage cars. These cars aren't quite old enough or harsh enough to have to start using 20/50, but they were designed to run on mineral oil and if the 10/40 you are using is semi or fully synthetic you're just going to add to the problem This after all is just my personal opinion and I know there will be peopel happily running on these oil, but one of the most important things to ask is how many miles a month does the car do a month? A car that does 2/300 miles a month is going to take 3-4 months before it will need a pint of oil. If like me your's is a daily drive and covering around 1000 miles a month you'll be using a pint of oil a month, this is perfectly in guidance with what they were using when new! Anything more than that and you should be looking to change it. Oil of choice for me is Castrol GTX High Mileage 15W-40

 

[Copperman05]

TBO I would have thought the difference between 10W and 15W is slight, and I would hardly call one thin and the other thick. These cars were designed to use synthetic oils that why porsche recommend them as high performance oils in the manual (at least for my 1989 S2 it does). How does using fully synthetic oil add to the problem exactly? Seems to be alot of mis-information on oil going around and around.... I get quite annoyed by it all...(in case you didn't notice)[] Edd :Edited for bad spelling.

 

[Bob]

ORIGINAL: Copperman05 Seems to be alot of mis-information on oil going around and around.... I get quite annoyed by it all...[]

Me too. A 10w mineral oil and a 10w synthetic oil are the same viscosity when cold, that's what the 10w means. The synthetic version will resist breaking down under extreme heat better than the mineral version - that's the difference

 

[Alexw]

I second Castrol GTX HM 15w40 - I read a review of oils somewhere that showed of the modern oils it has the highest amount of something called ZDDP which helps with cam wear. Modern oils have less of this as many newer car have roller tappets which don't require it. I can't find the article now though.

 

[Copperman05]

Perhaps, but if your so concerned about engine wear wouldn't you want to protect your engine from winter cold starts as much as possible? We all know that this is where most of the wear occurs.... Edd

 

[Northern924]

A lot of it is personal chocie in the end, The handbook for the reg. 944 doesn't mention anything about using mineral or synthetic. I've always used mineral oils in older engines, not a mechanic but as the engine wears you've more chance of losing/burning up more oil. Yes these are high performance enignes but the 20+ year old as well. As I keep saying its all down to personal choice I always used cheap thick supermarket oil in my n/a '24s and they were very happy on it, the 924S had GTX HM and used around a litre every 1000 miles. My '44 has done 163k so there's no way I'd use a modern oil in it, I've done just over 1k since I went back on the road and I've just topped it up, 3/4 litre so I'm very happy with GTX HM. Its right synthetic oils don't break down as quick and are recommended, but a mineral oil will be thick and with the right additives provide extra protection to old engines. Its really hard to say what is right for cars of this age, I'm happy with mine, other people are very happy using synthetic.[]

 

[JM1962]

I guess it depends on what you mean by drinks oil. Normal could be up to 1.5 litres per 1000km according to the handbook, although I would find this a bit excessive. If she drinks oil and she isn't leaking then she must be burning it. As a rule of thumb, smoke on acceleration = rings or bores, smoke on overrun and startup = valve seals or guides, although there could be other faults like crankcase breathers. Sometimes you can see the smoke better at night in the headlights of the car behind. I use Mobil super S 10w40 as it was recommended by a couple of independent specialists for older engines and is cheaper than fully synthetic.