Not directly related to whether or not it should be used as an OEM oil replacement, but for those using Mobil 1 "synthetic" and thinking it is a top shelf oil it may be worthwhile to do a little more research. M1 has changed its base stocks after petitioning the gov't about some of the other lower quality synthetics that were marketed as such without being true synthetics such as Pennzoil, Valvoline, and Castrol. Mobil failed to have the gov't disallow the use of the term "synthetic" in their names with the base stocks that the other manufacturers were using so Mobil has changed their base stocks to the cheaper organic base stocks that others are using. There are only a few true synthetics that are still out there that are either Group 4 or 5 base stocks. Those include Redline, Amsoil and a few others, FYI. I guess the point I'm getting at is while M1 may be a decent oil now, it (in my opinion) is no longer a good or great oil.