I believe it’s a lithium based which you can use Timken bearing grease if you want or Lucas Red n Tacky. If you’re repacking you can put Lucas x-tra heavy duty if you want. My understanding is you’re not supposed to mix certain types of grease and I forget what X-tra heavy duty is but it’s not supposed to be mixed with lithium grease. The issue with using the zerk fitting to add grease is it can go past the rear grease seal and get on the brake pads which you’d have to replace your brake pads and rotors if that happens. If you do use it, raise the wheel off the ground, spin the wheel while pumping the grease in, the grease should come out from the side you’re pumping. Keep pumping till you see the new grease coming out, it uses a lot of grease this way so have a few tubes on hand and hopefully it doesn’t go past that rear seal. Oddly enough the manufacturer recommends only using the zerk fitting for an emergency, not sure when that’d be. I’m the original owner on mine and it was way past due and found the bearing on one of the wheels bent a little causing it to bind a bit and another the grease was starting to go past that rear seal. Other benefit with pulling the rotors is you can check your brakes and make sure everything looks like it’s in working order. My father in law did his and had to replace one of his brakes as the wires were all messed up. It’s not hard to do, just time consuming. If you do pull the rear seal and repack, I’d get a repacking tool as they don’t cost much and speeds up the time it takes unless you like doing it by hand.
