I used Prestone Dot4. I also flushed the fluid in my fiancee’s 2005 Rancher 400 automatic using the same fluid. She bought this in 2009 and it has not been done since she has owned it. The fluid was very dark through the sight window. One of the screws for the master cylinder lid would not come out and I stripped the phillips head on it. I had to use an easy out to get the screw out and luckily I found another screw at the hardware store that worked.
To flush the fluid, I sucked out most of the fluid from the master cylinder and then added new fluid. I then used my Mityvak brake bleeder and drew the fluid through the bleeders until the fluid ran clear, making sure to keep the master cylinder full. I did this on both sides. It did not take long at all.
Does anyone else do this on their ATV’s?
Wayne