Ohh.. I reccomend using a engine flush before changing to amsoil, and if you have dino oil in it the first time you change to synth or amsoil you will experience what seems like your engine burning fuel or it breaking down, but what it is, is the synth dissolving your oild oil (the stuff you couldn't get out) so your oil may look dirtier than it is, and you may have to add a little after the first few weeks, the next time you change you won't have to worry about that. But it does clean your engine out. So my reccoemndation is not to swithc to amsoil or any synth with any old and tired engine, unless you have been using syth forever, if you have over 100K ondino or mix, you should prolly stick with it, otherwise you could get some play in your parts, and maybe even piston slap from all the deposits dissolving.
Hmmnn.. not sure what else.

Jay