Red Line Synthetic MT-90 75W90 GL-4 Manual Transmission Fluid

Red Line has become a household name in racing due to the quality of products they offer and the reliability they have sustained. 

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...?
Their specific formulation has the appropriate coefficient of friction for most manual transmission synchronizers while still flowing very smoothly (many other gear oils, engine oils, and ATFs are too slippery for proper synchro engagement yet are thicker when cold).
As well, the wide and controlled viscosity of pure sythetic 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. 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.

MTL is a low 70W at very low temperatures and a high 80W, nearly an 85W at elevated temperatures. This provides adequate viscosity to prevent wear and deaden gear noise. This is a thiner gear oil, almost as thin as ATF and works well in many applications that call for ATF such as many BMWs

MT-90 is a thicker version of MTL. A true 75W90 GL-4 gear oil (similar to SAE 5W40/10W40 engine oil viscosity)
Ideal when MTL is too thin and a bit thicker oil to help Syncros come to speed is desired. Better for "loose" transmissions than MTL, in many cases. If you have tried MTL and your gears seem to "clash" try MT-90

Red Line MT-90:


• Specialty lubricants intended for high performance & heavy duty use
• Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that can cause damage
• Exceeds API GL-4 standards.
• Excellent choice in many manual transmissions (especially those that shift best before the vehicle is fully up to temperature)
• Satisifies the gear oil viscosity requirements of 75W, 80W and motor oil viscosities of SAE 40, 10W40, and 15W40
• Recommended for GL-1, GL-3, and GL-4 applications, as well as where most special synchromesh fluids are specified
• Most customers require 2- 3L.