I don’t know much about the acid or alkali resistance of cheap RTV but I do know that it comes in two types, one type is acid based and the other is alkali based. If you apply the wrong one, (alkali), to an aluminium joint it will eat away at the metal and the seal won’t last very long. If you apply the acid one to a sealed electrical box, the acid fumes released during curing will corrode the electrical connections.