7500 miles on the GC in my V6 Audi, now I changed it, fresh and pure GC goodness. It took an extra .5 quart at the dealer, they asked if I wanted their oil added to make up the extra .5 quart. I declined and topped off when I got home. This made me wonder if my (local)mechanic from last time added some of his TropArtic to top me off. That is why I did not do a UOA, I added GTX and some M1 as I went along and I know how you guys are about mixing oils in a UOA. Now I can addd just GC if I want and get a GOOD UOA in April. Anyway, My car is extra perky after this change, just like most oil changes, I don't believe in the "Placebo Effect", sorry...it IS smoother, and GC gives an extra bump in this department.