Chuck Schreiber

Great time in the Hill Country last week!!

I wanted to check how much oil the car would consume, so I made it a point to not add any during the trip last weekend. The car uses very little around town, probably half a quart about every 1,000 miles on avg.

I put right at about 700 miles on the car last weekend. Most of the spirited 100mph plus blasts were on Saturday only and I'm guessing that was around 120-150 of the miles I put on her. Going down and returning to the event were just steady crusiing.

I used right at about a quart, the car just turned 80K, and I do not have a shark vent.

I don't want to get into an oil consumption banter on GTS motors, etc. I just wanted to know If this is about right for the car. It's on the high side of what I've seen over the last 4 years, but again, we were hitting it fairly hard on Saturday's run.

Grassy ***!!

andy-gts

I was behind you in group 2 and saw quite a few puffs of grey smoke on acceleration....just thought you knew. sorry I didnt say anything...

andy

Chuck Schreiber

Thx Andy,

BTW, sorry I did not get a chance to take a look at your motor, wanted to see the setup!!

heinrich

Chuck, when they have severe issues, they go as high as a quart/100mi. But that is last legs stuff. Seen it on the old Barry Johnson GTS, before any work. Your quart/700 miles is probably normal for a GTS with classic oiling issues. Sounds like you boys had fun, wish I could have again joined you. Last time was insanely fun.

WallyP

There is another factor which needs to be considered. A gasoline engine generates just over a gallon of water vapor for every gallon of gasoline burned - just the chemical reaction of burning fuel. Especially when the engine is cold (less than full operating temperature) part of that water vapor goes into the crankcase as blow-by, and condenses there. If you don't get the oil up to full operating temperature (which take quite a while on a 928!), the moisture stays in the oil. After a few months of relatively short trips, you can have a significant amount of water in the oil.

When you put the car on the road, and the oil get to full temp, the moisture will evaporate and exit the crankcase. This can result in the appearance of an increase in oil consumption on a trip as compared to around-town driving.

Only you can estimate the effect of this factor - but it could change the apparent oil consumption noticeably. Next time, check the oil on the second morning of the trip, then again when you get home. Make sure that you have the same conditions - cold engine , level front-to-rear and side-to-side, etc.

Herman K

Following Jim and Roger on the Friday test drive of the course did take a quart by it self

But seeing Jim spin out and keeping up with the Shark tuned GTS was priceless.

There is a big difference when you really step on it or drive it “Charlie” style

brianrheffron

+1 on WallyPs comment.
I had an old SAAB 99 used mainly for short range commuting.
I took it on a 300 mile motorway trip mostly at about 80 mph
and when I checked the oil at the destination it was very low.
I'm going back many, many years so can't give an actual amount
but it was enought to make me wonder if there was something
seriously wrong with the engine.
Anyway, I topped it up and on the return journey at similar speeds
I didn't use any oil. I concluded that either petrol or water had
got into the oil and had then boiled off during the long fast run.

Big Easy Sharkster

Chuck, my consumption on the '94 varies from 1qt/300 miles to 1qt/700 miles. Unfortunately, the GQ (garage queen) often doesn't get out but once a week. In this case, the increased consumption. When I do the annual trekk to SITM (700 miles each way), the consumption gets better as the trip progresses. I have no sign of 'blue smoke' and no carbon residue around the tail exhaust pipes

IcemanG17

I'd say you are fine

Oil consumption is always "high" in GTS's...probably due to the increased pressures the longer stroke engine creates and the "better" breather that allows MORE oil to get into the intake.....that with extended high rpm running is going to force oil into the heads & its only path from there is into the intake....

I've also noticed that GTS's do "puff" under load....at least the stock ones do....I'd guess it also contributes to the known pinging problem that GTS's also get....it doesn't take much oil to bring down the octane level of fuel....

Lizard928

Has anyone measured to see if there is any oil getting by the valve stem seals on the GTS?

Rob Edwards

When I disassembled my dead '93 GTS engine, I pulled the cams, took the heads off, drained the oil out of them, and stuck them on a shelf. How would I check the state of the valve stem seals and valve guides?

Lizard928

If you filled the heads with oil you could see how much leaked through.

However you could remove the valve springs, and then remove the valve stem seals and inspect them for wear.
To measure the valve guides requires you to have a dial indicator, the process is in the manuals.

I ask as I am wondering if they might have changed parts, or not held great tolerances....

Herman K

I saw the same when I followed Jim's GTS and he has made me aware when he was behind me that I have the same symptoms.

On the way back from 3rd coast driving slow as Brent was following us with a tire issue we hardly used oil according to my dip stick readings before leaving MF and after we returned to Dallas.

Talking with Brent about oils during his tire lay over at our house he mentioned that since he had switch from Mobil 5-40 to RP 15-10 he no longer is using any oil in his GT

ZEUS+

Only the intake valve seals will leak into the combustion chamber of a running engine if bad. It would take along time for oil to leak past a seal without vacuum or pressure if you filled the heads. A quick check is to use a thin liquid like gas. Just a small amount in the intake and exhaust ports to see if it leaks past seal. Flush with brake clean and lube after testing. The proper way is to disassemble and check for wear as suggested.

IcemanG17

the highly inprecise way I determine is the valve seals are dying is to look at them.....if they are clean (meaing the cylinder head around them), they are fine....if there is lots of black carbon around them, they probably are leaking.....I've only seen a few that were bad, all in 32V engine...but it is possible that is was just an engine that didn't have enough "italian tune ups" too...