Compounding valves is never a good idea. As the engine heats up the area that is mated will change and the seat doesn't work quite as well to seal. It's a band ad for a quick valve replacement if you need it. Plus the compound is very hard to get rid of if you're messy. If you must use it though clover is the better choice and you get two for one. Fine and course. There are other brands too. Do a search for lapping compound