We design VP Classic® SAE 80W-90 API GL4 Gear Oil for yellow metals and other soft metals (bronze, brass, copper, etc.) found in most classic manual transmissions. You can also use it for other soft metals found in manual transmissions and transaxles. For instance, synchronizers, thrust washers, bushings, and more. If you own a classic car, it's important to choose the best gear oil to protect both the soft metals and your investment. We recommend its use in traditional manual transmissions such as Rockwell, Muncie, Borg-Warner, Ford, and Saginaw. It's also perfect for import manual transmissions/transaxles that call for an API GL-4 gear oil.