Amsoil is second-rate snake oil in my book. Make sure you look at whatever fluids you choose and ensure that are *certified* to the appropriate standard (API, etc.) as required in the owner's manual. Some Amsoil products "meet XYZ standards" but don't bear the official certification mark and aren't really certified. This is Amsoil's way of saying that they think the fluid should be certified, but they haven't spent the money to actually have the certification process performed.

In my opinion, you're trashing a bunch of perfectly good fluids. Dump the oil at 1K... swap over to a full-syn like Mobil 1 if you want, and you'll be just fine. What do you hope to get out of changing all the fluids to Amsoil?