Everything I have heard about "Amsoil" is positive--here is a comment that needs adressing I think--I have been running Castrol for ages--change oil and filter regular every 3000 miles with a bottle of STP. Heard about Amsoil 0-30w--good feedback--one question--after running "regular" oil for 149k miles-->Will "switching" to Amsoil 0-30w make for problems due to normal wear on bearings-pistons-piston rings? Will the Amsoil 0-30 be so "thin", so to speak, as to "slip past" the rings and start to cause oil burning?-and will engine bearings--such as rod bearings--have problems since they are naturally not as "tight" in clearance as when the engine was new?? Have heard Amsoil 0-30 is best run on "new" engines only-. Another question is--if using Amsoil--how is the compatibilty with it and oil additives--such as STP, and would it even be "necessary" to use an additive? I would hate to switch to Amsoil now and find out one really should NOT switch, especially with 100,000 miles or more on the engine--albeit--with 149k on our '89 wagon, the engine still seems to be in "near perfect" shape-no leaks-no burning-still feels "tight".
The choice to go with Amsoil is I have heard it is a great oil--very stable--should be able to go over 10,000+ miles between changes, etc. Comments?? Thanks.