I'm running RP w/ syncromesh in my trans it it shifts smooth. It is thinker then the stock stuff so on cold starts it sucks but once warm I feel it shifts much better. I'm also running RW 75w140 in the rear with no issues. As far as engine oil, I just buy whatever is on sale as I've never noticed any difference in motor oil since I change my oil regularly anyway.
2003 Corvette Z06 - MGW shifter, Corsa X pipe, Corsa Xtreme exhaust, Texas Speed long tubes w/o cats, PowerStop rotors/pads, Conti DWS tires, C6Z51 F&R sways, C5R headlights, tuned
04 GTO - sold