Is this excessive oil usage on 3.2

Brent Lineker · Brent Lineker's Garage

My friend just picked up a 1986 911 and he and I drove it from Phoenix to Vancouver with no issues except for quite a lot of oil usage.He had a leak down and compression test done before purchase.Leakdown ranged from 5% to 10% and compression was 168 to 172 across the board.All records dating back to purchase were included with no motor work repairs evident.The car has 107 k's on it and was using a quart of oil every 400 or 500 miles.Would this be considered really bad or just normal for an engine with this mileage.It appears all service was done on time .

jorian · 11-23-2007, 06:36 PM

As low as 300 miles per quart is within factory spec. 400-500 is however, quite low compared to most 3.2's witrh similar mileage. As a comparison my 87 with 138K miles burns a quart every 1500-1700 miles. My SC burns even less. A friend who also has an 87 has to add a quart every 300 miles and is planning a top end rebuild this winter.

3.2's suffer from pre-mature valve guide wear which is evident on decelleration. A puff of blue smoke can be seen from the tailpipe. As it gets worse it will burn blue at idle as well.

Eagledriver · 11-23-2007, 10:00 PM

That is a bit excessive. Your friend should plan on replacing the valve guides in the next year or so depending on how much he drives it.

-Andy

Brent Lineker · Brent Lineker's Garage

Thanks for the replies,he is going to drive as is for now and plan on doing the top end next year or year after.

Rot 911 · 11-24-2007, 05:33 AM

Quote:

Originally Posted by jorian

As low as 300 miles per quart is within factory spec.
3.2's suffer from pre-mature valve guide wear which is evident on decelleration. A puff of blue smoke can be seen from the tailpipe. As it gets worse it will burn blue at idle as well.

I do not believe 300 miles per quart is within factory spec. I think it is 800 miles per quart. 400-500 miles per quart is an indication you probably are getting close to at least a top end rebuild. 300 miles per quart is flirting with disaster. I'm speaking from experience. I was using 300 miles per quart and when I did my rebuild found a burnt exhaust valve. All the valve guides were shot.

Oh and I never had any smoke from the exhaust as the oil was getting sucked out of the exhaust valves and not the intakes where the oil would be burned.

craigyirush · 11-25-2007, 02:20 PM

Actually the factory spec is 1 litre/1000 km!

I asked Bruce Anderson about this and he said that Porsche was being conservative (as well as calibrating what usage would be at high speed on the autobahn).

Pete Zimmerman says normal usage for a 3.2 is 1000 miles/quart.

My 86 Targa (w/220k) gets about that (with as high as 700 miles per pint).

Oddly, when I drove from LA to Calgary to Vancouver this summer I got 1840 miles/quart.

JackMan · 11-25-2007, 02:27 PM

I have a 3.4 liter with a some mild work done to the valves and cams, 10.3:1 compression pistons and 20,000 miles on the engine. The car burns about a quart every 400 miles. Engine is strong. No blue smoke on decel, just a bit of a puff at start up. No leaks. No greasy residue in the tail pipe.

Just a thirsty motor. I even participated in the rebuild at my mechanics shop. Aren't all motors just a little different? Like people with their accents?

wj

p911dad · p911dad's Garage

My 84 Carrera is over 100K and uses maybe 1 qt in 1500 miles, if that. In the last cycle of oil change(1 year, about 2000 miles) it was just over 1 qt. The oil is 20w50 Mobil 1. The engine has never be apart.

Wil Ferch · 12-01-2007, 07:31 PM

Hint.. a lot depends on the original level. If you fill near the "top" level, oil will expand when warm and will find its way into the intake tract where it will be consumed. Tendency will be to note the consumption, and then AGAIN refill to the high mark. Therefore, you will have "apparent" high oil consumption. If, OTOH, you fill to the mid-level mark, you will likely find much lower apparent consumption. So.. what was your reference mark ?

Mr.Puff · 12-01-2007, 08:28 PM

I think I use a quart every 900 miles. 1984 Targa =).

--Puff

Edit:

Oh yes. 211k miles with a rebuild at 109k miles.

EarlyPorsche · 12-01-2007, 09:10 PM

My 997 uses a quart per 6,000 miles (car only have 7,000 on it) but my 1966 2.0 flat-six doesn't burn anything much! It has a couple leak spots so I replenish because of that but the leaks are tiny. Those early engines are built like rocks. Anyway, watch for leaks, if its not smoking and the plugs are clean and its got that good leak down and compression then the valves can't be bad. I would replace the plugs, adjust the valves, do an oil change, and run thicker oil. It could use 20W-50, the person could have something thin in there by accident.

Mr.Puff · 12-01-2007, 10:29 PM

=P I use 15W-50... For some reason my auto-parts store doesn't carry 20W-50, but since I'm in California it doesn't matter.

Super_Dave_D · Super_Dave_D's Garage

Absolutely a quart per 400 miles is very high consumption. That’s what I was burning before my top end. Now its about a quart per 1500! Your flirting with disaster IMO.

HarryD · 12-01-2007, 10:53 PM

When I was using 1 qt/300 miles, my car looked like this:

After my guides were replaced, I get about 1500 miles/qt.

Brent Lineker · Brent Lineker's Garage

Well the weird thing is there really is no smoke on startup,my 75 smokes at startup but uses 1 quart of oil every 2000 miles,his 86 is using a quart every 400 miles but no leaking at all.I followed him in my car and noticed some puffing during accelaeration after a vacuum situation but really not a lot of puffing.As for adding oil during our trip home we usually put oil in to the half way mark or so but never over filling it.We couldn't find any Brad Penn,Swepco,Mobil-l or such so were just using 20w-50 from the gas station we were at.I am thinking he may be better off in the meantime with some thicker diesel type oil such as Rotella 15w-40 or chevron Delo 15w-40 until the inevitable top end rebuild.