Castrol TranSynd 668 is a premium, full-synthetic automatic transmission fluid specifically formulated for Allison Transmission on-highway automatic transmissions. TranSynd 668 provides oxidative stability, anti-wear performance, and friction durability, as well as TES 668 specification differentiators such as extended anti-shudder durability and extended clutch friction durability. This fluid features an Allison TES 668 approval. The TES 668 spec is fully backwards compatible for TES 295 applications.
- Delivers improved gear protection.
- Delivers extended anti-shudder durability.
- Delivers extended clutch-friction durability.
- Excellent corrosion and foaming resistance.
- Excellent thermal and oxidative stability that helps to prevent deposits and oil thickening.













Luke Pelletier –
Thanks
Mike Miller –
Showed up a little late due to snow but boxes were in perfect shape. Did some research and it appears that this is the same fluid as Allison transend just different label and manufactured by castrol
Rodney Cox –
Good price on bulk products and fast shipping
Mr. MacGreggor –
Very expensive but good stuff. My Allison transmission in 02 2500HD Duramax was slipping when it shifted. After changing fluid, the shifting is smoother going from 1st into 2nd. I believe the shop that last flushed the transmission used low grade transmission fluid…this stuff definitely made a difference.
Robert P. –
Makes transmission shift smoothly.
Martha account –
Worked great
Aaron –
This is what you need if you have an Allison transmission!
95sanger –
My Allison 3000 is gonna love this stuff