hydro shop tech says run in hi or low keep hydro coolers clean reservior should be warm to the touch he said NH removed an additive from hytran he sees glazing of plates on hydro pumps he recomends a universal trans fluid hi-quality!I use Chevron, a lot of our harvest days consist of 100+ degrees, you guys north may get by a little cooler & with drier conditions, we'er running tracks now in rice, 2nd hi, a lot easier on the drive train just slow in reverse