Best transmission fluid?

[Lenny5160]

Originally Posted by Jim Hawkins

This is what I use in the race car, service truck and the Duramax truck. A friend of mine works on Allison transmissions and says it is a extended interval oil, 200,000 miles. Works for me.

That's pretty much in line with the information I have found. It might not be 'better' than anything else under normal conditions and regular maintenance, but it will not break down under extreme heat and/or for a longer period of time than other fluids.