I have a d15b7 with a little over 222k miles. I've owned the car for a month now, and I've noticed it has an oil burning issue. I'm losing about half a quart of oil every week. But I'm trying to figure out if I have bad oil control rings, or bad valve guide seals.

I have performed a dry compression test and the results are in order:

205, 205, 205, 215

So I know the compression rings are good, but that does not tell me anything about the oil control rings. I do not have access to a leak down tester, so I have not done that yet.

When the engine burns is after I first start it up in the morning, I will get a little bit of smoke and the smell of burning oil. This leads me to suspect the valve guild seals.

Also another time it smokes is when I accelerate hard, once I hit 4k RPM I notice a lot of blueish colored smoke all the way to red line. It will also sometimes smoke when I decelerate using the transmission. From my research this leads me to think it's the oil control rings.

So with the information I've presented, what is most likely the culprit? The valve stem seals, or the oil control rings? Or maybe both?

I have a good low mileage y7 head I can put on if it's just valve stem seals. But if the general consensus feels it's piston rings, I would rather just deal with burning oil than spend money honing, and repairing the cylinder walls, installing new rings, and main/rod bearings. Because I do have a z6 I'm in the process of rebuilding. But have no plans of having it in this car for a few years.

Any help would be greatly appreciated, thank you for all the help.

 

Valve stem seals. The oil will seep down and pool on top of the valves overnight. Sounds healthy otherwise, good compression. Keep feeding its habit and be happy. Cheaper and easier than engine work.

 

I will probably just pick up an adjustable cam gear. Then throw my y7 head on it that I have. I was also thinking it's probably just valve seals, but wanted other opinions as well.