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, its important to choose the right 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. Its also perfect for import manual transmissions/transaxles that call for an API GL-4 gear oil. Do NOT use Classic 80W-90 GL4 gear oil in applications that require a GL-5 extreme pressure or other gear oil quality. Do NOT use in applications calling for an OEM specialized lubricant. VP offers a complete line of automotive lubricants, oils, and fluids for various applications to meet your needs.