Kevin, I checked all of my oils in stock and all were gf3 except for the 5-20 citgo which was gf4, even the mobil 1 5-20 and 5-30 were gf 3 and the 15-50 had no gf rating. I wonder what the quick lubes are using for oils ? I know that the gf4 5-20 is not cheap... Login to read more.