I fill mine with 6-6.5 every time. And i prolly use about a half a quart per oil change interval. I also have 130,000 miles on my car...and go thru 3-4 bottles of nitrous during that time too...with the 75 or 100 shot i might add

Still kickin'...for now lol

1999 Cougar V6 MTX SVT UIM/LIM/65mm TB, I/H/E, Fidanza/SPEC III/Torsen, Koni/GC's, 19" Icon wheels w/ Pirelli rubber, NX Wet Kit