[MatthewAMEL]

Tremec doesn't recommend ATF in the 6060.


If you read the spec, the data says 'Recommended for motor vehicles with manual gearboxes that require GL4 75W85 MTF, synchromesh, or DEXRON®-III/MERCON® fluids. Not recommended for automatic transmissions or hypoid gear differentials.'


If you compare the specs of the TREMEC fluid to Redline D4 for example, you'll see significant differences. Even basic ones like weight: 75W85 vs 70W80.


My conversations with TREMEC led me to switch to their fluid.


GM wanted a 'one size fits all fluid' so the DEXRON III is close but not optimal in all situations.


Also, which viscosity are you reading? The TREMEC fluid is:
Kinematic viscosity @ 100°C, cSt (ASTM D-445) 12.1
Kinematic viscosity @ 40°C, cSt (ASTM D-445) 71.6


https://cdn.shopify.com/s/files/1/0135/1637/4075/files/specifications.pdf?5237232191582097329