Chrisp3

I am in the hunt for a good used 928 (preferrably a GTS) and have spoken to several folks over the past week or two. One car which I thought I was interested in has 79,000 miles on it and needs some TLC. Somehow we got on the topic of Oil leaks and and the current owner made the comment that he has to add a quart of oil every 2nd or 3rd tank of fuel but hasn't noticed any significant leakage. When he said that I wanted to drop the phone and run but then decided that I ought to give the car the benefit of the doubt and ask the experts. I have no idea if this is normal or not in a 928....but it sure makes me stop and take pause.

Is this normal or abnormal? Can anyone give me a feel for oil consumption on a 79,000 mile engine?

unit

My 89 doesnt use any oil.!!

I changed the oil 4000km's ago and the oil level has not dropped from full.
The engine have 162,000 kms

I know ive read here that allot of people have a small amount but im unsure what "normal" is.

Good luck

Herman K

It is normal for the GTS to consume oil. The rate of consumption depends on the type of oil used, the speed you drive, climate and road conditions. I think you'll find most GTS engine to use 1 quart per 600 - 1500. I'll drive mine spirited and I'll use 1qrt / 700-900 miles

1994 GTS 5 spd

GUMBALL

Mine uses less than 1 qt in 3500 miles, even with "track days"... Engine has 200k miles.

Bill Ball

Two-3 tanks is 650-1000 miles. For most cars that would be said by the manufacturer to be "acceptable." Porsche quotes a qt per 500 miles for the GTS. Many use that much. Porsche replaced a number of engines that used even more.

My 89 at 185k miles does burn any oil between yearly 12K mile oil changes. However, it will blow massive amounts out the breather if I cruise at over 150MPH (legally in open road racing).

NickT

My '88 doesn't consume any either and has 160K on the clock. I don't add any between oil changes.

underdog928

I just changed my oil and in 3,500 miles it was down only about a qt.

'85 with 155,000 miles.

SwayBar

This is correct for GTS engines due to their pistons not having oil drain-holes drilled in the oil-ring ring-groove. If you do a search, you'll find lots of info on GTS oil consumption.

All other 928 engines do not have an oil consumption 'problem' when in proper repair.

AO

That means I must hve something to fix... like main seal, I think.

This winter, I promise my car will be leak free - and not because everything leaked out.

SwayBar

Andrew, I thought you replaced your rear main seal; is the front leaking now?

After I replaced the rear main seal on the engine that came with the GT racecar, it leaked worse than before! That motor is going into my street car, but only after I reseal the crankcase/cradle with Loctite 574 (?).

AO

I don't know where it's leaking. I know it's worse when I've been under boost.

It's coming from the front, but I'm not sure exactly where - I used to think it was the tensioner, but that's not it. Oil pan gasket has been done, and I'm pretty sure that's not the source either. I need to do the TB this winter, so I'll tackle it then. Also need to fix the PS lines. But then it will FINALLY be leak free!

Chrisp3

Thanks for all the input. I appreciate it very much. Don't yet know how that affects my decision, but at least I have more information now than I did a few hours ago.

IcemanG17

The spec for oil consumption is 1 liter or 1000k.....or about a qt per 625 miles.....

On Mobil 1 15-50 mine used about a qt every 4K or so....but on amsoil 20-50 racing...it doesn't burn hardly any inbetween yearly oil changes....

I did find that after I changed the oil thermo springs the oil consumption went down a bit, even with M1

GregBBRD

If a GTS uses a quart every 2-3 tankfulls, it's a good one. When you have to add a quart every tankfull....that's not as good.

Aatos

Used oil type will heavily affect oil consumption. I doubt any of the guys reporting 0 consumption use 0/5W-40/50 synthetics.