Disregard any thing writen by amsoil they make a good product but the stuides are way slanted.
Belray is a good product and will serve you well.
The Spectro Platium is about the best for six speeds but hard to find.
Redline, roal purple all the 100% true sny GEAR lubes will do fine in the tranmission.
Avoid SNY in the primary.
M1 VTWIn 20/50 is a fine engine oil you will find others as good but not anything much better.
Besides with all this rain and flooding the bel-ray that traces it roots back to boat engines might be a good idea
You have some good stuff it just ride