There are many antifreeze types that will be suitable for your tractor. Problems can develop however when two incompatible types of antifreeze are mixed together. If your new antifreeze is not the same type as your old, you have the potential for an unhappy chemical reaction between the two. It can be a simple sludge or deposit formation, or it can be as bad as acids developing that will cause your engine and radiator harm. Simply draining the old fluid does not get every last drop out. The way to avoid this is once you drain the old, be sure to thoroughly flush the system with fresh distilled water. You may need to do this several times until it comes out clear. If you don't want to go through the trouble of flushing, just be sure you re-fill with the same type (doesn't have to be the same brand) as what was in there previously.