911 oil comsumption

Hi all,

I have a 1988 911 that seems to be consuming quite a bit of oil. It only burns oil when first started (I am told that is normal) & after it is running, seems to not burn at all. It doesn't leak a drop either. But I am contanstantly adding oil. Any thoughts?

They all seem to use about 1 quart per 1,000 miles

I drove an '88 Carrera for four years.
It did need an occasional half-quart between regular changes, but it didn't burn oil excessively.
If your 911 uses a quart of oil every 1000 miles, it's in need of some serious attention...probably NOT from the guy who told you "they all seem to use about 1 quart per 1,000 miles."

With a variety of 911 engines, including three different ones in the spyder... A fair variance of oil consumption depending on the engine itself, the wear on the engine (especially valve train), and how much the engine actually leaks.

We have an old 2.0 liter engine hanging out at the shop that is quite a leaker accompanied with some smoke on startup. That engine uses a quart every 500 to 800 miles. In truth, it is leaking more than it is burning so the oil return tubes (this one leaks there) and the valve covers gaskets were replaced last weekend. We'll see how it goes.

The 2.5 (from a 2.4) that we originally put in the spyder was a miserable pig. Lots of smoke on startup and frequently a fine haze while driving. It also leaked... When that engine got down to 1 quart every HUNDRED miles, I did a compression check on it. I think my best hole was 110 pounds hot... Major, big time overhaul would be needed to make that right.

Two different 3.0 engines. One has about 90K on the clock. That is a pretty "dry" engine with nothing more than a small puff on startup. A quart, maybe quart and a half every 5,000 on that engine. The other 3.0 had about 120K on it. Started up the same, but did have a few minor leaks. A quart every 2,500 to 3,000 miles.

The short stroke 3.2 in the spyder (built from one of the above 3.0 engines) is a very dry engine - the only leak on the car is the stupid transaxle. That engine uses less than 1/2 a quart every 3,000 miles. So, maybe 1 quart every 5,000 miles?

The 3.2 in Steve's cabby hasn't been driven, but we have all mechanical records on it. The engine is an 85. The mechanics notes indicate oil consumption at 1 to 1.5 quarts every 3,000 miles. I have records for this engine dating back to 1988. The oil consumption has increased from "no change" to 1 to 1.5 quarts every 3,000 miles, indicating that on this engine at least, there was no discernable oil level change at 3,000 mile oil change intervals.

The mechanic from whom we purchased this engine suggested that when oil consumption got down to a quart or more every 1,000 miles, that the valve guides needed replaced. He was unconcerned at this point (1 to 1.5 quarts every 3,000 miles).

Not trying to start a flame war here, as I don't know how much oil you are actually using, just wanted to add some info. Also, though you probably already know this, be very careful to only check the oil level when the engine is fully up to temperature... With the front oil cooler, all that oil in there can dramatically expand with heat.

angela

Wow John, I agree with you but that was a bit of a slam. I have broad shoulders and anything you can dish out, I can take.

Sorry about the typo, it should have read 1/4 quart every 1,000 miles
Which is the average consumption of the 7 Porsche's I've owned since 1969 coupled with the 131 factory cars I've had since 1971

131 cars? Good heavens Larry, you are indeed a gentleman car farmer.

angela

Angela,
Those 131 cars were Porsche Factory test cars. I drove for them from 1971 through 1991.

Porsche flew me to Detroit, a factory employee would pick me up and drive me to Ann Arbor to the EPA test center. I would then drive the tested Porsche back to California, write up a report and keep the car until my next trip. Back then, I was always able to take time off work by trading days off and on many occasions I had 2 cars to bring back and I'd take one of my friends from work. On one occasion, my dad went with me (that was a funny trip).

Sometimes, Porsche would send me to Denver where the cars had to undergo high altitude testing and again, I'd drive them home, do a report and keep the car until my next trip.

Geez, that sounds like a shitty job. NOT!!

Larry - very sorry.
My comment was not aimed at you, but rather at the guy who may have told you that kind of oil consumption is normal for 80's era 911s.
My point was - it may be "common" for some mechanics (who are too lazy to delve into it)to repeat that myth, but it's not normal and should be remedied.
I wasn't sniping at you...honest.
Again, my apologies.

Thank you and graciously accepted

Larry,
Once again I envy your past job... The very fact that you actually got PAID to do that is incredible. It would be like me getting paid to ride my bike. Probably the only people who would pay me to ride my bike would be Jenny Craig or Weight Watchers...

angela

Angela,

I'll give you a buck if you ride your bike. Send me an invoice

I raise the bid to $1.25 :)

I'll take your picture, then put it on eBay and send the proceeds along to you. You may caption the picture as you please.

Those Nigerians will probably bid it up pretty high ;>)

The valve guide solution sound pretty right on target But I would check the jugs for out of round wear while you have the heads off as a precaution. being very careful not to disturb the rings. A mike set in the jug horozonal set snug will show lose verical. The more lose the mike the worse the jugs are egged..

Do replace the valve guides, does the engine have to be pulled? Is this big time $$?

This topic usually causes a flurry of activity on Rennlist and Pelican Parts boards. I follow those threads closely since my other toy is an '87 Carrera with 98k on the clock. It seems that the general consensus is that premature valve guide wear affects Porsches from 1974 to 1998 (last year of the air-cooled).

A good indicator that you may have premature valve guide wear is excessive oil consumption. One quart per 1000 miles is about the standard amount for the 911 engine. Many (but not all) Porsche enthusiasts (or at least the ones that post on the boards) believe that when you have to start dropping in a quart every 500 miles or less, your oil consumption is starting to move into the "excessive" range.

The most common recommendation to fix the problem is a top-end rebuild, which generally costs $4-6k. There are less expensive and more expensive fixes (e.g, a complete rebuild), however.