Congratulations and welcome to the group Arno.

I haven’t hauled the boat just to service the prop shaft.  My C-drive oil remains clear.  I drop the bow thruster after 2 years to check the oil in it and so far it has remained clear and no loss.  I rarely dock so the bow thruster gets very little use.  I put 4-500 hours a year on the engine.

A word of warning...nothing else sticks to tin-based paints.  To recoat with another product, the hull has to be completely stripped (in a closed environment in the US).