Originally posted by mr_froge:
AMSOIL is the first 100% sythetic oil to receive the API certificate. The reason that no other AMSOIL products or anyother 100% synthetic have this certification is because of the formulation of their long extended drain interval products. I Quote: "As of July 1, 2002, AMSOIL INC. of Superior, Wisconsin, re-formulated its XL-7500 line of synthetic motor oils to meet API SL/ILSAC GF-3 certification standards with the use of Synthetic Group III base oils.





Thanks for the particulars, Rich. As I had to let my Amsoil dealership go 9 years ago when I took a job with AT&T, I haven't kept up with subsequent R&D in fine detail.