Brush hog gearbox...oil or grease?

[Soundguy]

grease alone wil cavitate unless a 0 or 00#.. #2 or #4, the common gun greases are not suitable for gear boxes.

I have in a pinch used them with a 25/75 mixeof gear oil to make a soupy that slumps if I can't lay hands on a 0# grease..

soundguy

 

[jbwright]

Are the seals that hard to change? Never had to do one.....

Depends, I have done a few. Some you can take off the stump jumper with a wrench on the nut. Some require a 3/4 impact and a torch to heat the nut they can be very stubborn depending on age.