Sounds like a generic term, "friction modifier" being used to refer to two different things, in two different contexts. I understand your use. In the context to which I referred, it prolly should be referred to as "limited slip additive", and often is, although
this amsoil product, designed to be used as a differential additive, is referred to as a "friction modifier".
I think that we understand each other, and I'm not trying to pick nits, but rather to define some terminology so others aren't confused. Sometimes I even confuse myself, and I'm not trying to do that, either
Back to the oils. As I said, I used a lot of Mobil 1, but not since '90. Chances are probably good that it was
not "energy conserving", or at least did not have some of the newer additives, back then. Makes it a new ball game, if so. Does it say that it is "EC" on the label?
Just looked @ a quart jug, and yes it does, as does one from about 4 years ago.
MOBIL 1 info