I've used both the off road Racing Oil, and the regular VR1 racing oil in my GN.
About 5K miles a year in a 3 season driver.
No issues at all with Valvoline in about 20K miles I've used it in this car.
I change it and the filter at around 3K miles.
Never seen a sludged up Turbo Buick motor that was driven regularly, regardless of what type oil used.
You don't need additives with that oil.
Indeed. This is a great oil. Bruce used to use it all the time as well, swore by it. I also used to use it my Buicks before I went to RP :biggrin:
If your having to order oil, you might want to check into Brad Penn. You'll be hard pressed to find a dino oil any better. Very impressive stuff.