I'm asking this mostly just for clarification to make sure I'm not jumping to conclusions and repairing the wrong thing. Here's the situation:
Car: '87 560SEL
Mileage: ~110K on engine (220K on car)
Performance: excellent all around
Oil Consumption: ~1.5qt between 3,500 mile changes
Oil Smoke: none at speed or decelerating but frequently on acceleration especially if idling for a while; also can be considerable when idling in traffic for lengthy times (5-10 minutes) and at warm temps (80F+ ambient)
Oil Used: I'm not too particular on brand but have always used an appropriately API rated national brand dyno - changing weights hasn't seemed to make much difference (adding some 90W gear oil does). The problem hasn't changed much in the one year and 20K miles that I've had the car.
I'm thinking that the problem is just the valve stem seals, a rather common occurance for the 117 engine from what I can tell in searching here. I have checked compression recently and got very good results - all 8 cylinders in a 5psi range around 175 - so I doubt anything in the bottom end.
My concern here isn't so much the actual oil consumption but rather the very obvious smoke on acceleration and while idling. It can be somewhat embarressing and I don't want it to become an inspection issue.
I'm going to do the valve stem seals soon anyway as the timing chain and guides are due for replacement and once I have the valve covers off I might as well do the seals. I just want to make sure that if there is something else that could be the cause here, I cover it while I have things open.
Thanks in advance for everyone's help. This board has been very educational and enjoyable as well as a big $$$$$ saver