# GL-4 Manual Trans Fluid info...



## Auto Union (Dec 25, 2010)

Relevant to the thread that got locked, some basic MTF info...


GL-5 is GEAR oil for diffs, GL-4 is Manual Trans Fluid/Lube for manual trannys.


A synchromesh GL4 Manual Transmission Lubricant (MTL) can be any viscosity from 7.0 cSt (ATF equivalent viscosity) to a 75W90 type viscosity of approx. 14.5 cSt, and contains special friction modification additives for synchronizer assembly engagement.

A synchromesh fluid usually refers to a specialized fluid that contains special friction modification additives for transmissions that use mechanical synchronizer assemblies; those synchronizer assemblies may be made of carbon fiber composites, sintered metal, brass/bronze, or steel-steel materials.

Current synchromesh MTL GL4 viscosites are:

1. ATF Series - Type; 6.5 to 8.5 cSt (Equivalent ATF viscosity; Note: ATF additive package is weak compared to most GL 4's)
2. Synchromesh Series - Type; 9.3 - 9.5 cSt (such as Amsoils MTF, Texaco's MTL, Pennzoil's Synchromesh, GM and Chrysler's Synchromesh)
3. 75W85 Series-Type; 9.8 to 11.5 cSt ( Redline's MTL, RP's Synchromax LT, Nissan's MTL, Honda MTL, Castrol Syntorq LT)
4. 75W90 Series-Type; 12.8 to 14.5 cSt (Amsoil's MTG, Redline's MT-90).

MTL specific lubes we're developed for manual tranny's and transaxles, and not for differentials or industrial gear boxes, so their viscosities will not match most viscosity charts.


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