This is the first vehicle that I have ever owned that I run the cheap gas in. Almost all previous vehicles took premium. So anyway I am on my 3rd tank since I got it and when I accelerate from a stop, once in awhile I will get that initial ping storm and then not again. Haven't noticed it at all during normal driving. Should I switch to medium or not worry about it?

 

Is it the 5.0? Mine done the same thing. Continued to get worse. Took it to the dealer. They tried a few things and ended up getting Ford involved. They stated that the 5.0 is a high performance engine and premium fuel is recommended. After they directed me to the owners manual it does in fact say this. Not required but recommended. I normally fill my truck up when it gets to around 1/2 tank. I will finish filling it up with 89 then the next tank 93. Since i have been doing this the knocking is almost non existent. The truck also runs 100% better as well. It sucks having the added cost of premium fuel but i love the truck and love the way it runs with premium. Really hard to describe but the entire truck just seems to run smoother.