Gl4 should be fine in my opinion. It's also the specified lubrication for the transmission as well as the transfer case both of which see long continued high pressure use. That said given the robustness of the winch you could probably run it packed full of butter.....
I'm joking of course but what I'm trying to say is- just about any gear oil would probably give you a lifetime of daily service.
Peter
I'm joking of course but what I'm trying to say is- just about any gear oil would probably give you a lifetime of daily service.
Peter