Thanks for the ideas so far, guys. I don't see any blowback from the oil filler cap, and the road draft tube puts out a little light smoke, but nothing real heavy, at least at idle. I use straight 30w, non-detergent, and go through a quart about every 200 miles, plus a sparkplug. Agree with the advice that it may be easier to put up with it that try to fix, but I also read somewhere that replacing a valve seal isn't all that difficult. I'll try the Restore first.
