My 1996 850 GLT (133k miles) is losing oil. I've gotten into the habit of checking my oil every 1k miles, and I find that I have to add a quart or more when I check it.

Although I have not found oil on the ground under the care, I've had it to the dealer to check for leaks. They can't find any.

The car seems to run fine, and passes emission tests, so I didn't think it was burning the oil, but where else can it be going?

I've always been good about changing oil every 5k with synthetic oil, and Volvo or Mann filters.

Has anyone else had similar problems with an 850? Any other suggestions on what I should be checking?

Thank you.
-Tim