The one thing I'll add to Jcamper's story is some marketers (Exxon, Chevron, BP, 76, I know of), add twice the additive to keep your engine cleaner. Unfortunately, Valero is not one of the companies that add twice the additive. The Costco, Safeway, or high volume retailers (HVRs) add the absolute minimum additive. The Valero, ARCO and other
oil companys add a little more than the HVRs. This additive is very good for your engine and is required by the EPA.