 If your engine doesn't leak oil, but you have to add to it between oil changes, where does the oil go? The problem occurs when piston rings clog with carbon and then allow oil to blow by the pistons and burn in combustion chambers. The best service shops use a BG product that cleans the engine in just 15 minutes. Find a shop with BG products at BGfindashop.com. That's BGfindashop.com.