You may be aware of this & odd as it may sound, but most non-marine grade grease are somewhat to very water soluble as (I think) they're made from clay/lime particles as a thickening agent for it's petroleum oil base (partic the hi-temp, nonmarine stuff)... there's even mention of soap & other organics used but times change & I could be wrong;
lol *shrug* no matter what it's actually made from, as I'm an all season rider (rock salt & calcium chloride in the winter) and
live on the coast - I've noticed a distinct difference in the longevity & properties of various grease types & I've tried more than a few...
hesitation whatsoever I'd recommend giving this stuff a shot: Multi-Purpose 2-4-C With Teflon
... costs a bit more than the cheapo stuff initially, but it's insane how long it lasts & defo lives up to it's "extremely water resistant" claims