AMS Oil
 

Tried the search button first but it returned zero results. But is anyone using ams oil and doing the extended oil changes? Used it in my truck up to 20 thousand miles. Just checked the oil every few thousand to ensure it wasnt low.

I used Amsoil in my Z for one service interval (5,000 miles) - works just fine. But there's no way I'd go 20,000 miles in between oil changes (and if you do, make sure you also use Amsoil's extended service interval oil filter too).