Brothers of the Benz
Rich, your 1986 300E has one of the strongest if not the strongest bottom end of any of the Benz engines.
Unless you have an untold amount of miles, 200,000 or more, or has been grossly abused, your rings should be just skuffing the machining marks off the cylinder walls.
The valve stem seals my need replacing, this is a routine repair above 100,000 miles.
Have the valve stem seals inspected and replaced if needed; then check your little puffs of blue smoke. Chances are you will have corrected the problem but if not, what will be an acceptable oil consumption rate?
My 1987 300E W124030 and the same engine has 175,000 miles and it uses a quart of oil between changes.(3500-4000mi).
Being the original owner I know how she has been maintained. Sometimes when we purchase pre-owned, we gamble on the care our beloved Benz has had.
My engine has the original valve stem seals. I attribute the long life to regular oil changes. I've always used dino oil, if I could do it over I would have choosen synthetic. Who knows what mileage I would obtain considerring what I have to date.
I'm hoping to get 200,000 miles before any cylinder head work. It appears I may make it if the valve seats and valve angle don't wear out.
Oil is cheap and seals ain't.
Happy Trails Beep Beep from The Spiderman in Houston!!!