i asked why m1 seems to be 25% more than SOPUS synthetics at wal mart...he said it is because M1 is the BEST oil on market and that if i want to buy good oil like pennzoil, QS or shell i can...i dont think m1 is worth the xtra money myself, even i though i like it a lot...QS full syn is only 17.48 at WM as opposed to 23.74 for m1..pennzoil platinum is 19.00...shell full synthetic is 21.99 for six quarts at BJs wholesale in new england as opposed to 36$ for six quarts of M1...i will use s the shell thank you very much