Not so much bad in our eyes. I think the ECU will disengage it once you go over a certain MPH. There is a mod you can do to bypass it only being used in 4LO and be able to use it in 4H and or 2H. Google it. I'm sure it's out there.First thing I'm going to do with my 13. , get out of stuff in 2wd, I got told driving over 15 mph with the diff lock on was bad. Anyone know why?