Always used Penrite, will switch to their 10 Tenths racing stuff for my next change as its doesnt mix with E85.

Gbox oil, just use penrite too. Nulon also are very good as are Royal Purple ($$$)

As long as you are using a reputable brand i would make sure its changed regularly of course, thats the most important thing. The better quality oil you buy will last for longer under stress so you can extend your service intervals.