The truck crane that I have, is comprised of two parts, one is bolted
to the truck bed and has a round vertical column, and the second part
slides over the column and swivels. It has a lubrication port for a
grease gun.

I want to put some grease in it, so that it does not rust inside, and
also swivels more easily. My question is what grease to put. I
generally have been using green marine grease everywhere, for example
in casters that I keep outdoors 100% of time.

Would this also be appropriate here, given our cold winters.

By the way, the crane is supremely useful and I regret my wasted youth
and all those years when I did not have this crane.

i