America's Definitive Marine Engine Magazine
1. Be hyper-vigilant. Watch for engine error codes. Monitor engine temperature and water pressure.
2. Frequently clean outboard motor and stern drive lower units using a solution of biodegradable detergent and water. Whatever detergent you use, be sure to choose one with minimal environmental impact. On inboard and stern drive engines frequently check the seawater filter for fouling.
3. With a stiff bristle brush frequently clear oil fouling from the cooling water intakes to insure full flow of coolant. Watch engine temperature like a hawk!
4. Seawater impellers exposed to crude oil will swell, ultimately leading to impeller failure and likely engine overheating damage. Similarly, crude oil also attacks rubber propellers hubs. They soften, weaken and the rubber hub spins inside the propeller. Some larger horsepower engines do not have a rubber hub, but instead a Delrin hub. Delrin is impervious to crude oil.
5. Back at shore flush internal cooling passages by hooking up to a fresh water faucet. Collect and dispose of contaminated waste water according to local marina guidelines, local authority regulations and/or the Clean Water Act requirements.
6. Clean the anodes. If the oil won't come off, replace them. Anodes are located in the heat exchanger, oil coolers and catalyst exhaust manifolds and elbows.