I would not run 30w in a Michigan hydro. Too cold up here for half the year. Stick with atf or universal tractor trans/hydraulic fluid. They are more in the range of a 5w20. Just my opinion. Paul
FYI - ATF and UTFs shouldn't be grouped together regarding viscosity. The vast majority of the universal tractor trans/hydraulic fluids are in the 30W viscosity range while most ATFs are in the 20W range. There are a few low temp UTFs out there that match ATF viscosity but not many. They will list the Deere low temp spec J20D as opposed to the normal Deere spec of J20C.
Here are the Deere specs for their two UTFs: https://jdparts.deer...onHydraulic.htm
The viscosity @ 100*C number determines weight range.
Edited by Canawler, October 24, 2015 - 03:22 PM.