Redline MTL

Redline MTL is a synthetic manual transmission fluid which improves shifting smoothness. As a synthetic, it also has a lower pour point (the temperature at which it will still pour) than a comparable natural petroleum oil. Some owners report the improvement obtained by Redline MTL fades after a year or so.

Sometime after 1989, the MTX-IV went from brass synchro blocker rings to fiber lined blocker rings. During a shift, the synchro moves sideways on the countershaft and locks the counter gear, which is otherwise free-spinning, to the countershaft, so it can transmit power to the countershaft. Prior to the synchro locking the gear to the countershaft, the blocker ring engages the gear and spins it up to speed, so the synchro can smoothly engage the gear. It accomplishes this by shearing a film of oil between the blocker ring and a mating surface on the gear face. MTL has much higher shear strength than ATF, which is why it shifts smoother then most ATF's, because it can bring the countergear up to speed faster. It takes a few miles and some heat for the ATF to get worked out of the fiber liners, which means shift improvement from MTL will work in gradually with '90 and later transaxles.

Redline D4