oils is oils , you have been watching too many Castrol GTX adds.
Fuels is fuels and it's designed for one purpose as well but I wouldn't be putting std unleaded in my GTR.
I have seen vehicles signed off before the work is even done so don't take that as gospel.
As I said ( and to get back on thread ) assume nothing and do it yourself.
I agree with Dave , oil is relatively cheap insurance and as Enrico said , he has allowed $450 so that should cover the basics with quality gear.
Cheers
Ken
Your right , no ones listening so don't waste your time