Originally Posted by BumbleAbout
- which trailer bearing grease should I use?
I think any reasonable wheel bearing grease is fine; key is to watch for problems as Pete explained above. Top up or inspect and repack every now and then, and as long as you don't have water ingress, or a mis-adjusted hub, things should be fine.
- will it have any effect on the bearing grease already in there if I top up with a different sort of grease?
Stay with the same soap base, and you'll be fine. If you worry about existing grease, solvent wash the bearing carrieres and wipe out all you can from the hub and races. Repack with your chosen grease, and you're good to go.
One advantage of an Al complex base is the water resistance; the disadvantage is it's incompatible with Li complex soaps that the rest of the automotive world uses. Makes it tough to top up if you're in the middle of nowhere.