Originally posted by mr_froge:

So, what is it that allows AMSOIL motor oils to be used for extended drain intervals, while other oils must be changed significantly sooner?



That would be the litigious nature of the US legal system, coupled with AMSOIL's big cahunas.

Many people have been probing the limits of Mobile 1, and so far, nobody's really found it. That's on an oil not formulated for extended drains, but I would think that Mobil 1 would be safe up to at least 10k for most people, based solely on the inherent advantages of synthetic. But again, for legal and liability reasons, Mobile 1 makes no such claims in the US.

As for Amsoil, a 25k mile drain interval is a bargain if you actually drive that far in 6 months. (Oh yeah, the other drain interval.) I'm lucky to drive that far in 60 months. So, basically, I'd be changing my Amsoil just as often as I change my Mobile 1.

I'm not saying it isn't a great product. But, it was designed/optimized for tractor/trailers, not low-mileage daily drivers. Mobile 1 gives me all the synth advantages I need at considerably less cost and hassle.

Function before fashion. '96 Contour SE "Toss the Contour into a corner, and it's as easy to catch as a softball thrown by a preschooler." -Edmunds, 1998