I put in new stem seals a year ago - along with a couple rocker arms that were beginning to spall. I noticed one valve guide was getting worn...but with the few miles we put on our SL I am going to let it go for a while...it will certainly lead to premature stem seal failure but the cure ($$$) is worse than the disease at this point. No smoke yet...

Also this summer I spent a load of dough to have the "ball studs" replaced, along with a re-shimming of the valve train. The thing about changing rocker arms and ball studs is that you are supposed to "adjust" the clearances via shims, which requires a special tool...and shims, of course. So unless the rocker arms are starting to spall I would just leave them...

I agree dealing with the "cones" on the valve stems is a PITA!! A magnet and hemostats were critical for me...and if you drop one...you can have a heck of a time finding it again...BUY SOME EXTRAS BEFORE DOING THE JOB!!!

best,

Dave