We all know that oil is the lifeblood that keeps all mechanical parts operating with minimal friction and/or damage. With that in mind, you hopefully realize that using the incorrect oil—while still lubricating parts—can and will allow damage to occur. Such is the case with a recent transmission the folks at Silver Sport Transmissions were tasked with taking a look into.
The folks at Silver Sport recently had a TREMEC transmission come back for shifting troubles. The customer had used an unapproved fluid. In this case, the fluid was too thick, which slowed down the synchronization and caused gear clash. This in turn damaged the clutching teeth of the gears and synchronizers. Unapproved fluids can also react with and cause damage to the brass blocker rings.
When you get your manual transmission installation kit it comes with an installation manual. On the very last page, you will find a list of acceptable fluids for use in your transmission. It is very important that you use only these recommended fluids. Other fluids will void your warranty, and for good reason.
We found the following questions and answers about approved fluids on the TREMEC website.
Q: What type of fluid does TREMEC recommend?
A: For all TKO five-speed models, TREMEC recommends TREMEC HP-MTF, GM Synchromesh, or Mobil 1 Synthetic ATF. For all other aftermarket models, we recommend Dexron III ATF
Q: Why use automatic transmission fluid in a manual gearbox?
A: Some TREMEC transmissions are designed specifically to use automatic transmission fluids (ATF) for good shift quality in cold conditions, compatibility with synchronizer friction materials, and minimized parasitic drag to maximize power to the wheels.
Q: Why not use hypoid gear oil?
A: Hypoid gear oils are designed to withstand sliding actions at the meshing interface of bevel gears. Some hypoid oils contain extreme pressure additives that are corrosive to certain non-ferrous metals that are used in transmission parts like bushings and synchronizer rings. Also, the friction coefficient of some hypoid gear oils may be incompatible and can cause poor shifting. Both of these conditions can result in premature or excessive wear and failure.
Q: How often should I change my manual transmission fluid?
A: Under normal driving conditions the fluid should never require changing. For severe driving or racing, fluid changes should be made frequently, especially when operating temperatures of the transmission fluid exceed 250 degrees.
So, even if the oil you’re considering comes in a flashy container, cost much more and promise you the world… don’t fall for them! Use the approved fluids and your transmission will shift smoothly for years to come.