Hi Kiwi,------- Don't beat on that aluminum oil pan with a block of wood & hammer. If it cracks you will cry & so will your wallet. Best way to soften that gray sealer is with a heavy duty heat gun that is capable of around 500*F. ---------

Heat around the area that you suspect is holding for 15-20 min. The sealer will get soft like chewing gum. Keep the heat going until you see the gap between the block & pan starting to flex, then it will break free.
Those Germans use tough RTV. Good luck---- Ray