I had the same problem on my '86 560 Sl. I had the car checked out especially compression and everything was good. It started to use a quart of oil every 200 miles. I had the valve seals replaced as well as the timing chain and guides for $1400. and now it uses nothing...no oil use. Hopefully that is your problem for the mechanic told me if that doesn't fix it it'll need a valve job in the vicinity of $4000-$5000. Hope thats all it is . Good luck.