Fogging: Winterizing Your Boat’s Engine

Before putting our boat up for the winter, one of the winterization processes is fogging the engine. What we mean by fogging the engine is protecting the inside of the engine’s internal parts from corrosion and moisture that will take place during the wintertime and that’s due to the temperature changes throughout the winter that causes condensation.

So, with this, Sierra offers a fogging oil that will help protect the inside of the engine that’s also applies to stern drives and inboards as well, we’ll want to fog them before we put them up for the winter. Sierra’s products are a synthetic blend package. This actually helps enhance when we’re fogging to minimize the amount of smoke that comes out of the exhaust so it’s not a heavy smoke, okay, and it also conditions the air inside much better as well.

On some applications we have a fitting where you would use like a gallon of fogging oil that would bring the oil through and treat the internal components that way. As well, we have a spray bottle, and in this case on an outboard, what we would do is we remove the silencer, we’d hook up the earmuffs to the lower unit and make sure we have an adequate supply of water. During this process, we only want to run the engine at idle. We don’t want to run it too fast because we might not have enough water to supply the engine and it could cause some engine damage. So from there, we want to start the engine with the adequate water flowing, we want to run it at idle. We’re going to take the spray bottle from Sierra’s fogging oil and spray it directly into the air induction system.

While it’s running, you’ll start noticing the engine is choking down. That means we’re getting the oil inside that’s going to start treating everything internal. Coming through the air intake also helps us treat the reed valves, everything below the piston, and then on the top side of the piston it will help treat the cylinder walls and the rings and the pistons and those components.

So when we’re done, as the engine chokes down, we could go ahead and shut the engine off. So, from that point, what you want to do is take the spark plug wires off and remove our spark plugs. Of course, we want to pay attention and mark our wires to which cylinders they went to. And at that point, when we have the plugs removed, we want to spray a liberal amount of fogging oil into each cylinder and then you can go back to the starter and just spin it over a couple of times, that will help disperse all the fogging oil inside.

Now from there, we’re pretty much ready to put it up for winter storage. A couple final points on fogging, make sure the engine is always warmed up, and there are a lot of different engines out there so make sure you read the OEM manufacturer’s recommendation for fogging.

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