Redline MT-85 GL-4 is popular for owners with manual-transmission cars, as it does not contain the reactive sulfurs found in most GL-5 oils that cause damage, so it's safe for most manual transmission synchros. Other synthetic gear oils are often too slippery for proper synchro engagement, but MT-85 has the appropriate coefficient of friction, so it offers excellent gear and synchro protection, plus balanced slipperiness for easier shifting.
MT-85 has the same viscosity and GL-4 rating as factory BMW gear oil for 7/2011+ open/non-limited slip differentials. However, after research Red Line has determined that it's 75W85 GL-5 oil is a better product for this differential. Even though GL transmission oils should not be mixed, the differential does not see the same high pressures and the materials are not as sensitive. The 75W85 GL-5 is Red Line's official recommendation for 7/2011-later BMW non-slip differentials.
- Offers quicker shifts, perfect synchronizer coefficient of friction
- Eliminates notchy shifting
- High-performance gear protection and longer synchro life
- Recommended for GL-1, GL-3, and GL-4 applications as well as where most special synchromesh fluids are specified