You can use modern sealants or coatings but for a weekend driven classic, we always like to use a good wax when the car isn’t exposed to the elements on a daily basis. The metal trim and rubber seals also need special attention. The metal trim can be stained or pitted when not properly cleaned. The seals are sometimes old and hard to replace so cleaning them and conditioning them is key. The light fixtures on many classics are also not as watertight as newer cars. Avoiding a heavy stream of water is key to avoid any moisture in the housing that may cause future rust or electrical issues.