Newby here... I just got an Evinrude 15hp, and have a spark plug question. I want to replace the plugs. What is the correct plug number, and is gapping necessary? It starts right up, and runs good, just the plugs are covered with rust. This engine has been just sitting on a dinghy on a large boat for several years, without being run. I think I got a good deal on it at $550.