Red Line Oil's MTL and MT-90 are designed to provide excellent protection and improved shiftability for manual transmissions and transaxles, having cured the problem of hard shifting in thousands of transmissions with shifting troubles. How? They have the appropriate coefficient of friction for most manual transmission synchronizers (many gear oils, engine oils, and ATFs are too slippery for proper synchro engagement). And, the wide viscosity of MTL and MT-90 allow proper shifting over the entire temperature range which the transmission will experience. The synthetic base oils used have a very high viscosity index which provides relatively constant viscosity as temperature changes. MTL is a low 70W at very low temperatures and a high 80W, nearly an 85W, at elevated temperatures, providing adequate viscosity to prevent wear and deaden gear noise. MT-90 is a thicker 75W90 version of MTL. The shear stability and oxidation stability of these products are excellent, thus the physical characteristics of Red Line MTL and MT-90 will change little with use. Popular in Nissan, Toyota and Mazda manual transmissions and transaxles as well as other selected applications, this is a 75W90 GL-4 Gear Oil that's slightly heavier than MTL. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting.