I'm about to be rebuilding my 700r4 transmission. What transmission fluids are considered to be top dog, both conventional and synthetic? (price also being a factor.) What's your pick and why?

 

Heard a lot of good things about Synthetic Royal Purple, but have never used their ATF. When i use their Engine oil i see a 10 PSI boost in oil pressure. if it were me i would use it. it runs about $10-12 a quart.

For Conventional i would say dexron 3 but the new dexron 6 is suppose to be better and fully compatible with dexron 3 trannys, but im not sure if its synthetic or conventional. about $5-8 a quart.

"DEXRON-VI was introduced in 2005. It was designed to replace all prior specifications, and is therefore backward-compatible with applications calling for DEXRON of any type. The specification defines both a performance level and specific additives that provide improved shift feel, friction durability and oxidative stability compared to earlier specified fluids."

 

Dexron VI!

 

Since GM's latest ATF standard, Dexron VI, is a synthetic and fully backward compatible with transmissions designed for previous versions of Dexron, I woud use it.

 

so dexron 6 is fully synthetic?

 

Yes. A buddy of mine suggested VI as well. Any particular brand though?

 

Considering that it hasn't been a long enough length of time for GM to release the full formula, I'm going to say GM. That is what I will be using come spring when I service the transmission on my Rainier (and install a shift kit + servos, etc).

Everyone else that has Dexron VI fluid is just guessing at it formulation and stating that it is compatible based on the specifications of the fluid.

 

I bought the Castrol High Mileage ATF as my Blazer has 165xxx miles on it. What are your guys take on that?

 

I like Castrol products but it sounds like GM Dexron VI is the way to go.