.djtcz@comcast.net writes: The AMSOIL folks may have their own recommendations. Yes, AmsOil is compatible with dino oil but then the change requirements revert to the requirements for the dino oil. I've used dino oil to top off when near the AmsOil change time with no ill effects. The AmsOil company agrees. Ed Corson (CORSA member) IECC - Riverside, CA