While just the homesteading of these critters is bad enough, they have a habit of eating every wire they can get to, which is just about all of them. This includes wires to alarm systems notifying you of a oil injection problem, overheating and other such items that are there to protect the engine. If you've priced a new outboard lately, you can see where this could get mighty expensive. As far as outboard motors go, I highly recommend you schedule an appointment with a qualified outboard mechanic for a preseason check of your motor. A good pressure check of the cylinders can predetermine if you need new rings in your motor.
New rings are quite a bit less expensive to replace than a new head and cylinders.
Another good tip is if you haven't ran your motor in a while to have the impeller changed in the water pump. The vanes on these impellers will get memory in them causing them to not pump an adequate amount of water up to the motor causing it to overheat. This is definitely not good on a motor that's running at red line all the time. A good tune-up is very important to getting the most mileage out of your motor. Again, with the high cost of fuel, it's very important to get every bit of performance from it you can.