I replaced a qt of my oil for a qt of lucas oil (conventional) in my 4.0 GC at the recomendation of others to try to quiet the valve train. While it really did not help that, my MPG went up 1 MPG. This is based on my overhead (before and after), same type of driving. Needless to say I am surprised. Imay try it on my Hemi the next oil change, although that will get syn.