Replacement gears

We have a bunch of motors that are a bit past their prime. We were going to try replacing the gears with the replacement sets, but the lubricant on some of the gear sets has dried out (we inherited a bunch of VEX stuff of uncertain vintage). What kind of lubricant should we use? How often should we expect to need to replace the gear sets? I imagine with the new motors with the steel gears this will become less of an issue. We’re trying to save our budget and avoid buying all new motors right now, so we’re trying to get one more season out of our existing stock.


Just curious - how are the motors behaving in terms of being “past their prime”?