This is exactly right.

If it's stuck, more force will just increase the potential for more damage. Penetrating oil will not damage anything, on the other hand, and should reduce the amount of force needed to get it to budge.

Penetrating oil does take a little time and patience. But it's worked wonders on sailboats over the years, where one tends to find a mixture of stainless steel, aluminum, galvanized steel, and bronze in every-day use, mixed in with sea salt and bird poop.