"Larry" wrote
Where is the REFINERY?

Can't speak for Amsoil - IIRC they make it from scratch vs extracting
(refining) it from crude.

In any event there are very few refineries making many many brands of oil,
each one custom blended and refined for its seller. There is no
Harley-Davidson Refinery for example - they instead had a refinery make up a
very special additive package needed to deal with a unique problem affecting
iron-cylinder "Shovelhead" and earlier engines. Took them 240 long-term dyno
tests to find it. It was definately better than automobile oils *in that
application*. Owners who didn't believe that overhauled their top ends
anually and sometimes had valves stick open and hit pistons at idle.