Was planning on running Royal Purple engine, transmission and rear end lubes or Mobile One in the Engine. Was told today that synthetics attack the GM seals. Have used RP in all my Hondas and Infinitis with no problem. If this is true I guess I will go with CASTROL GTX dino oil. Anyone heard anything about synthetics in GM drive trains?:4-dontknow:

Corvettes come with Mobil 1 and mine has 72000 miles with no leaks.

I am curious who would have told you that! I have run synthetics in as old a GM (Oldsmobile Trofeo) as 1990 for thousands of miles with no noticeable effects. Do keep in mind, though, that synthetic oils will clean up any old gunk/ varnish left behind by conventional oils.