"I have used the heavy duty oil additive in every vehicle that I own, 1988 Suzuki Samurai with 200,000 miles, 1996 Suzuki Sidekick with 147,000 miles, 2002 Dodge Ram 1500 with 237,000 miles and a 2008 Dodge Grand Caravan with 157,000 miles. Recently my Truck that has a 5.9L(360) in it, started to idle rough. Found out that it was the heads that Dodge puts on these motors. Flame hardened on the combustion chambers, one exhaust valve had burnt through the seat, which is not replaceable. 237,000 miles on this motor and the push rods, lifters, cam, rocker arms looked excellent. Previously, at around 198,000 miles, I had removed the pan to check and clean after I discovered a leak in the timing cover right behind the water pump( oil/ water in pan) and removed one main and one rod bearing. To my delight, both looked in great shape and checked out fine. Thanks to one quart of LUCAS oil additive with every oil change (5000 miles). I also use the fuel injection cleaner to o. Will be trying some other Lucas products very soon. Thanks so much for keeping my vehicles in clean running condition." -Mark Drummond