I've got a 92 740t wagon, 150k give or take a few miles. The problem I am having is excessive oil consumption and white smoke at start up, that goes away once the engine comes up to temperature. The car is using about 1/2 qt of oil every 500-800 miles and the consumption appears to be dictated by highway (more) or city (less) driving. Oil consumption is basically the same on dino oil or synthetic oil. I am using Mann filters, the oil separator box is new, and associated lines are clean.

The car does appear to be leaking at the oil filter adapter plate, but it is not enough to leave any type of puddle underneath the car. The car will generally smoke a little each morning until the engine is warm and then it seems to dissipate. The car recently sat for a week and upon start-up the smoke was very thick and much more than normal.

I have no coolant loss, and fuel mileage and overall performance is good for this vehicle. I haven't checked the compression on the engine yet, and about a week ago the car threw three or four codes which were all associated with the FI unit and the Oxygen sensor. 1-1-2, 1-1-3, 1-2-1 and 2-2-3. The codes were reset and have not reappeared.

I have not been able to pinpoint the oil leak, but it does appear to be the filter adapter block, and possibly from other areas around/underneath the turbo. The leak does not appear bad enough to cause the kind of loss I am seeing in oil. Does the turbo likely have bad seals? Valve Seals? any other suggestions or ideas appreciated. Thanks