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Boat Engine Fogging for Long Term or Winter Storage (Outboard)

Written by J. Harvey / Fact checked by S. Numbers

boat engine fogging for long term or winter storage

Whether you’ve decided to take an indefinite boating hiatus or just want to winterize your boat, fogging your vessel’s engine ensures proper storage. However, not every boat owner agrees when it comes to the necessity of this practice.

It’s the process of using fogging oil on the engine to prevent corrosion, moisture damage, and other issues related to extended storage.

Is it worth doing? In this post, I’ve highlighted the value of boat engine fogging for long term or winter storage and shared a handful of nifty tips so that you’ll enjoy its benefits continually over time.

Meaning and Benefits of Fogging a Boat Engine


Fogging boat engines is but one process involved in winterizing boats. The keyword there is “winter”.

Some boat owners live in places that get too cold, so they have no choice but to “fog” their boat engines.

That is, they use an aerosol solution like fogging oil to coat vulnerable top-end components of the engine like the carburetor and cylinders as well as the intake (in an inboard) and exhaust, among others. You do all this so they won’t corrode or be subject to moisture damage.

In certain locales where boating during winter is more or less still viable, many don’t find the need to do this.

  • A couple of folks argue that the fuel from the engine acts as a protector against moisture and the elements already – at least, in the short term.
  • Some say they do fine with just draining the water out of the engine along with its lower unit when winterizing Yamaha outboard motors.

Nonetheless, if you intend to store your boat for a long time or over the winter, I highly recommend that you use fogging oil on your engine. To fog a boat motor is to show how much you love your precious vessel, especially considering what it will be up against while it’s in storage.

Here’s why I’m all for fogging boat engines:

  • You won’t have to worry about rust and corrosion problems plaguing your engine. Did you know that not fogging outboard motor places it at risk of ceasing or failing to start altogether?
  • The oil acts as a protective coat that shields your engine from damag
  • By protecting your engine against this threat, you essentially prolong its life.
  • Fogging the engine every time you store an outboard motor applies to every climate, not just those with especially cold winter seasons. After all, corrosion also thrives in highly humid areas and places close to saltwater in general.

What to Use to Fog an Outboard Boat? How Does It Work?


Whether you’re trying to fog a 4 stroke outboard or an inboard, there’s only one oil you need, and it’s fogging oil. Why? It’s made specifically to impart the protective benefits mentioned above.Fogging oil is designed to stick to the engine’s vital internal components and protect them for a long time. We can’t say the same for the other types of oils out there.

Are you curious as to why it’s termed “fogging”? We’ll have to look at the typical process of boat engine fogging to know why.

One of the initial steps in coating the engine involves starting and revving it up and then removing any filter your boat has. As you continue spraying into the engine’s internal parts, the exhaust will start emitting smoke (which is a great sign!), hence, the term “fogging”.

I said it’s a great sign because that means you’re coating the parts of the engine that need to be coated (such as the ones mentioned above) since they’re prone to corrosion and rust.

But that’s just one step, though. You’ll also need to remove the spark plugs and spray the oil on the cylinders.

I recommend watching this video that takes you through the entire process:

But what if you own an inboard? Well, the intent of coating the engine is pretty much the same.

When fogging an inboard boat engine, you spray on the intake or on the spark plug holes, as was shared above and demonstrated in the video.

Got No Fogging Oil?

If you don’t have fogging oil available on hand, don’t fret, as there are other fogging oil alternative options to choose from. However, I’m going to have to stress that nothing beats the actual thing, especially if you want to enjoy the complete benefits listed above.

1. Spray Lubricants

I consider this mainly as a supplementary engine storage spray, especially if I discover that I’ve run out of fogging oil and have to wait a few days or a week to get one. While they do protect the engine to a certain degree, the difference in overall reliability and longevity is vast when compared to most fogging oil products out there.

2. Regular fuel mixed with 2-cycle oil

This is another reliable cocktail I can get behind and one I learned from a boating buddy. Basically, the ratio is 1:9 of 2-cycle oil and fuel oil. Give a liter of that combination a good stir, and you’re good to go.

Be sure to not mess up that recipe, though! Or better yet, just have the patience to buy or wait for your fogging oil to arrive. If you know someone with a spare can lying around, then don’t hesitate to ask him or her some!

Tips to Prepare a Boat Engine for Long-term or Winter Storage


Inboard motors – For inboard motors, remember these pointers:

  • You want to keep moisture and corrosion from rearing their ugly head as much as possible. So, be sure to change fluids and oil filters beforehand and remove any trace of water in the engine and its individual parts, may they be the hoses, heaters, ballast, drain plugs, etc.
  • Empty the fuel tank completely or fill it to the brim then add a stabilize Don’t do something in between.
  • Look for any signs of damage on the propeller. If there are, it’s best to get it repaired before storage, so you won’t have to wait to get it fixed come boating season.
  • Do a thorough cleaning of your boat.
  • You have no idea how spare equipment and gear left onboard can become moisture culprits. Get them off before stowing your vessel!
  • Remove the battery.
  • Don’t forget about finding good storage for the trailer.

Outboard engine – Got an outboard instead? Keep these guidelines in mind:

  • You also need to change or replace your oil, especially if it has become contaminated, and remove the battery, too.
  • Carbureted engines will need to be drained of gas. If you’re fogging the engine, this should be automatic.
  • Refrain from tilting the motor up, especially if you aren’t sure that you’ve drained all the water in it. Otherwise, the water likely won’t drain, freeze up, and you may have fresh headaches (i.e. ice damage) to deal with come springtime.
  • Last but not least, make sure you clean the boat, including its engine, and stabilize the fuel if you aren’t leaving the tank empty.

When fogging your engines, here are some tips I know you’ll find extremely valuable once you put them into practice:

  • I’m not one of those boat owners without a stand when it comes to deciding the quality of fogging oil I’m going to buy. I aim for top quality, since I regard my vessel as no less than that.

Those offered by household brands like STAR BRITE, Quicksilver, and Yamaha remain solid options.

  • As for marine engine fogger products available, you don’t have to worry about finding a specific one like fogging oil for outboard or inboard vessels only. Most readily accommodate both.
  • Don’t pull your punches when spraying or even if it stalls your engine. You want a generous coat as much as possible, especially if you’re looking at years of storage.

Frequently Asked Questions


When should you fog an engine?

If it’s a question of necessity, do it every time you need to store a boat for a long time or over the winter. As for the time, it’s best to do it right before the start of the winter season.

Can fogging oil damage an engine?

If used incorrectly or on something it’s not compatible with (like a diesel engine), it may become an issue. Otherwise, these products were specially formulated to handle sensitive components like engines.

They were formulated to protect. That should already give you all the peace of mind you need.


Ultimately, boat engine fogging for long term or winter storage shouldn’t be skipped by any well-meaning boat owner who regards his or her vessel as a true treasure. Moisture, corrosion, and the elements can wreak havoc on engines, even the top-notch ones.

The fact that fogging works exceptionally well to prevent these problems should give you enough reason to make it a habit every season. Be sure you use the right lubricant, though!

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