I tried looking for The Official Oil Thread but hard to find on the old celly. I switched over to Royal Purple this past weekend. Gone about 50 miles with it. Started it up this morning and instantly could tell a difference. Alot quieter amd smoother running engine. Ive always used full synthetic so i know its because of the additives that Royal Purple uses. I recommend it to anyone. My engine is a 3.0 1999. With about 210000 miles. They have it at your local walmart too!