Originally Posted by donbrew

or, at the risk of putting amsoil jobbers out of work, you could just research changing oils. You will find that you have been strung up on an urban legend with absolutely no evidence. Changing between brands, between syn, between semi-syn, between organic is in a word "okay". Nobody has ever documented otherwise.

The very old time "service" station guys used to say that to keep customers coming back to only them, and somehow it stuck in the group mind. It is pure bunk!