I have a 1994 850 (non turbo). My first issue that I had to fix was the oil cap filler that I replaced. So we'll see if that's the problem. But the next problem that may be aiding in the loss of oil out of the oil cap area is this. The compression coming out of one valve is so strong, it's like an air compressor hissing when i open the cap. That seems like it's a little too much compression for one valve .

 

Turn the engine on, pop the hood and take out the oil dipstick. Do fumes come out from the dipstick tube when you accelerate? If it does then you probably have to service the PCV system. Cost is 150 USD DYI, I don't know how much it is at a shop.

 

Also have the cylinders checked out with a compression gage, if you suspect compression problem.


JPN