I just went to Checker/Kragen Auto Parts and saw this add for Duralube. I was wondering if anyone has used any of these products in there cars, and if they really work, their websites say they do but u know how they are. Duralube, Prolong, Motorkote, you know what I am talking about Some of these products claim horsepower gain like motorkote, look at their site. Has anyone ever used these? or do they work or is it a gimmick? Jimbo Jones 2004 Mystichrome Cobra 30,900 miles everyday driver Borla Cat Back Exhaust.