Get as large a tranny cooler as you can, keep the fluid out of the radiator, and run the regular Hy Gard. I even insulate the tranny lines next to the engine to limit the amount of heat that they might otherwise pick up there. The cooler than optimum temps will not do anything bad to our trannies. We just don't drive them enough to. That came from Lenny and is the way I have driven my cars for years now. And the only reason to add any ATF is to give the fluid some color that makes it a little easier to read on the dip stick. Otherwise it is not necessary. I don't add ATF, I just put some baby powder on the stick to read the level.
https://jdparts.deere.com/partsmkt/...draulic.htm#_Hy-Gard_and_low-viscosity_1 Me thinks there is a lot of misinformation made here, Dave
If your making over 700 HP then maybe this applies to your parts, I've been told by more than one good west coast tranny builders to have at least 160 F fluid temps on street drivers, not clder
Their recommendations were from 160 F up to 260 F, replace it if it starts to turn from bright red to dark red or brown or black.
I ran a tranny temp gauge in my last S/P car with a glide and a 5800 RPM stall converter shifting it at 7000 RPM that ran in the high eights in the 1/4 mile at 150.+ MPH, iI had decent tranny cooler on it mounted under the floor and the temps would get up to 170 F on the return rode driving back to the pits.
It wouldn't get as much heat in it at the 1/8 mile local track, maybe up to 150 to 170F in the summer after several runs
A1 said to change the fluid after 25 runs and adjust the front band at the same time, I did that for over 6 years and had no problems with it
