Amsoil is a great product. You don't throw it away like conventional oils, you simply change the filter at 10K miles and add a qt, then change both at 20K. Filters, you can't beat a Wix filter. Standard Fram shows where all their money is invested...in advertising! Cut each one open and compare. When shopping for oil and looking for the zinc content, look up the MSDS sheets on the product and compare the levels of zinc. It has to be listed. If the engine is used and has mid to high miles, sometimes it's best to step up 1 grade if you go true synthetic.