<VV> Stuck axle oil dipstick removal?

[Ignacio Valdes]

Hi, My differential dipstick is stuck in the tube probably due to surface
rust. I've tried pulling, tapping with a hammer, etc but it isn't budging.
Both the tube and dipstick are out of the car. Is there a good way of
freeing this up? Is there a good way of preventing this from happening in
the future? It isn't the first time and I've coated it with oil in the past
but here we are again.

-- IV