If you are trying to choose between STA-BIL and Seafoam, it really depends on what you need. If you are just looking for something to clean your engine, then Seafoam is a great option. It will remove any build-up in your engine and help keep it running smoothly. However, if you are looking for something to protect your engine from corrosion, then STA-BIL is the better choice. It contains a corrosion inhibitor that will help protect your engine from rust and other damage.