Antonio

You may want to consider the AOS upgrade kit. The stock breather depends on engine vacuum to suck the vapors out that the bypass tank does not have. Without vacuum it is likely to blow out the oil separator ring seal and end up with a major oil leak on an engine with this many miles.

944hal

I've had a similar problem. When starting the car didn't smoke. When the pipes got hot it did. Then it quit. Look under the car where the turbo and downpipe join. Any oil staining? My turbo was dumping oil directly into the exhaust. I installed a new rebuilt turbo just about a year ago. No noticeable smoke now, but I still use about 1/4 quart per 30 min session of hard driving. I top off after every practice session or race. Plugs are clean and I really don't have a lot of liquid in my catch can either. There is still oil in the intercooler and intake hoses but none is pooling in the turbo housing. Maybe you're just a shade outside of normal :-)

User 52121

Antonio - I also bought the Moroso cap (which adds vacuum back to the system).

944hal - From the best I can tell, I get no smoke. But it's going somewhere. I was really hoping it was the turbo. Really, really hoping. It's an easy fix (relative to pulling the motor) plus I'll put a better turbo in. But I don't think it's the culprit. I've got the turbo wrapped in a turbo blanket so I can't see the joint between the turbo and the downpipe, though looking up there last night from under the car, the blanket itself looks relatively clean. I'd think that I'd have some staining there if it were leaking. The only way for me to get that blanket off is to destroy it and I'd rather not do that, just to check to see if I've got oil leaking.

Monday night after driving home I noticed I had the all-too-familiar "oil on hot exhaust" smell. Argh. This is new, and it's not leaving spots on the ground, but it seems I have some oil weeping down the pan and blowing back onto the exhaust pipe. Rinsed everything down with brake cleaner last night, drove it today, will look tonight to see if I can spot where it's coming from. Did not notice any smells on the way in today. Fingers are crossed that perhaps what I smelled was a combination of (a) just some residual from when I last topped the car off and dribbled a little down the outside of the oil fill tube, and (b) some leftover "mess" from the last time I changed the oil filter (as that plastic tray under the car seems to catch a lot... and I drove it in the rain for the first time in months on Monday, so maybe it was some water/oil mix that just blew back off the tray and onto the exhaust).

Regardless, it's starting to look more and more like I'll just be pulling the motor this winter. Sadly the more I think about it, the less I want to do it! It gives me something car-focused to do over the winter but I just don't want to spend the time or $$$ this year and was really hoping for a year OFF from major expenses! (2 years ago I had the motor out for a full reseal job, and then last winter I did a bunch of remodeling on the house). Plus it'll cut into the budget I was setting aside to buy a 2nd 951 for my wife to have her own...

2bridges

Well omni that was exactly what I was experiencing when i tore down the engine in Freckles.

Though it ran strong, it experienced heavy oil use on track. My issue was a very badly scored cylider wall and piston. I have to admit i was amazed how well/hard this car ran inspite of a severely damaged piston/wall. It looks like a dozen geometric flat sides on piston and wall instead of round.

Only other indication was at cold startup sometimes it would smoke just a little until up to temp, then undectetable unless in boost.

Good luck, hopefully you will not find the same

2B

User 52121

When I had the motor out 2 years ago, the bores were in great shape - no scoring.

Startup is clean too. No smoke. And I paid close attention at this past weekend's AX when my wife was driving the car for smoke and the exhaust was clean....

The mystery continues...

87944turbo

Just curious, do you run the same boost level on the street and the track?

User 52121

I don't mess with the MBC at all and keep boost fairly low (relative to most folks here anyways). On the street (in other words, 3rd/4th) I generally don't see more than 13.5psi in the warm summer months (like now).

I was seeing just over 14 at Road America in 5th gear.

Rannem

I have the exact same problem as you.. Heavy consumption on the track, nothing when street driving. Compresssion in all cylinders are great. I run a k26/6 wich has around 1mm play. Almost no oil in pipes and cooler.

I assume it is the hotside of the turbo that is leaking. But when im reading the replies, it could also be som bad piston/walls.

Had any progress?

Lethal951

Remember that these engines have big clearances and if you use a light weight oil it will then burn... Try using a different weight of oil and see what that result gives you. I sorta had the same problem with the car burning about 1/2 a quart every 2000 miles or so when I was using 15w50. Once I changed over to Brad Penn 20w50 racing oil all those problems went away.

Rannem

Im currently running Pennzoil 25w-50 GT Performance

Lethal951

I seriousy dont think it could be a Piston/wall problem... How man miles are on the motor???

xsboost90

oil rings- my turbo actually used very little on the track or the street, but my fresh built n/a -stock rings still- uses a fair amount at the track. My first n/a- a 2.7- used lots of oil at the track and the rear bumper would be black pretty quickly. It was totally rebuilt except the rings.

Rannem

Between 85'-100' miles..

Rannem

As a comparison my -90 951 (Turbo S) has 170' miles and almost no oil consumption

Thats why i think the turbocharger is the weak point here..

Lethal951

I would agree with u on that one.... Turbo is blowing oil into intake