For the rearend Amsoil Severe Gear 75w140 ) no friction modifier needed its already in there)
M6 transmission use Amsoil Synthetic ATF
For the engine Amsoil Series 2000 0w30 Servere Service oil and a EA032 filter.
Using this stuff you should be able to go 10,000 miles between changes. But get an oil analysis done to be safe. Amsoil says you can go 35,000 on oil and 25,000 on filter.....so they say.....
I don't put on a lot of miles so I am going 1 year between changes should be about 6-8 k for me.
Enjoy your ride