My '88 300 SEL seems to have all the classic symptoms of needing work on the valve guides or seals (high oil consumption, a rare puff of blue smoke, occassional rough idle, pushing 100k miles, etc.) as I've read through many postings on the subject. Otherwise, she runs great. Evenso, I'm taking her to my mechanic to get a more precise diagnosis next week. I'm curious as to the repurcussions of just living with the symptoms (as none are particularly severe) depending upon the $$ we might be talking about here. I've heard elsewhere that the catalytic converter could suffer some if I don't take action, but that the problem is otherwise relatively innocent - I just have to keep topping off the oil with about 0.5 quarts every 100 miles or so - around once a week in my case. Also, what kind of labor hours should I expect for repair of valve guides or seals, and is their anything else I should look at while I'd already be into the labor costs of opening up?