I too wonder why no one makes mention of Valvoline Synpower. It may be a matter of what's widely known. I never heard of Amsoil until I started going to this website. I use Valvoline Synpower 5W-40 in my Passat which has the 1.8l turbo engine. On the back of the bottle it says it is "Mercedes-Benz 229.1 approved". Along with BMW High Performance Syn. oil Requirements, VW 500.00, 502.00 and 505.00 approved, all Rolls Royce/Bentley vehicles, and meets all Porsche performance requirements. The real important part for me is with regard to the European oil rating sys. A1,A2, and A3 for gas eng. None of Mobils xxW-30 oils meet the top rating of A3. Mobil does not sell any xxW-40 here yet, except at the local Mercedes dealer $$$$. I can not comment on Amsoil, I have never seen a container of their oil or researched their products. I would just stick with any oil that meets the A3 standard, which is for high performance and or long oil change interval requirements. The only Mobil 1 product that meets this standard is 15W-50. I have been thinking of switching my '83 TD from Chevron Delo 400 (conventional oil) to Mobil 1's 15W-50. I wasn't aware the Valvoline made a 15W-50. I'll have to go to their website and look it up. Problem for me is the availability of Synpower. Only my local NAPA store sells it and for the weight I use,I have to special order it.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section