Like alot of small block chevys of the 80's, mine has questionable valve seals at 45,000 origional mi. It lets out a blue puff of smoke when started after sitting 1-3 hrs...overnight, its usually fine. I use Vavoline oil and a AC filter, change every 3000, with no measureable consumption between changes. I've heard that a good synthetic, like Mobil 1 , while clearly not repairing problem, seems to help MINIMIZE smokey start-ups. Has anyone else found this to be true...or is it something we live with short of replacing seals? Comments? I do not believe in STP, and the like, but if someone could suggest an alternative, I'm willing to at least listen. Thanks.