Quote Originally Posted by tortron View Post
could be pinging? hard to tell without hearing it
When I first got my truck, I was able to run regular in it. Over time, I had to switch to mid-grade due to acceleration pinging. I don't think this was the fault of the truck, I think it has to do with gas manufacturing (and ethanol). It might be a good test to put some mid-grade in it, if you're running regular.