Lately I have been riding with the widows open and have heard a rattling while accelerating. I have been using the lowest octane fuel available, so I am assuming that my next fill-up with high test may cure the problem. (It seemed to run fine on it with the radio on). LOL. Any thoughts on using lower octane fuel, mixing grades, additives, ect... Also, anyone use a little Marvel's Mystery Oil, Lucas Oil Treatment, Slick 50, ect...at oil changes?

 

Fuel thoughts are : 10-1 compression four cam V8 = premium fuel. Using regular in this car is like putting AAA batteries in a flashlight designed for D batteries and wondering why the light is dim!

 

The '05 is 11:1!

The minimum you can use is mid grade. I'd use premium for a while, though. These cars won't live as long with detonation as the old cast iron boat anchors of past could.

 

Rattling vs. pinging (detonation)
If you are sure it's pinging, your ideas may be worth trying. The only reason I ask is that my car RATTLED on acceleration. Turned out to be the heat shield on the exhaust. The rivet had popped out allowing it to vibrate. Simple fix and it is silent again.