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Is Fogging a Boat Motor Necessary?

Written by Anthony Roberts / Fact checked by Jonathan Larson

is fogging a boat motor necessary

For first-time boat owners, fogging is a must-do to protect your boat. Engine Fogging involves a particular coat that acts as a protective layer on your motor’s internal parts. The process is similar to “winterizing” or preparing your boat for long-term storage. Fogging helps maintain the quality of your boat’s motor.

That’s why, if you come across the term and ask, “Is fogging a boat motor necessary?” You will discover in our short guide its many benefits and detailed instructions on how to do it. Among the advantages is oil-coating to avoid any corrosion.

Benefits of Fogging Your Marine Engine


Preparing your boat for winter storage entails tasks like engine fogging. Here are ways it proves useful for your investment.

  • The engine fogger spray serves as protection against corrosion, as the latter typically springs from humid areas.
  • Fogging oil is made out of safe chemicals that protect boats’ internal parts.
  • It keeps it dry, avoiding damage from moisture and elements, especially if your place is close to saltwater.
  • Extends the lifespan of your boat

When is Fogging Necessary?


  • Fogging is essential to do when the winter season is approaching. During winter, the air is drier or has lower humidity.

This may cause machines or motor-run appliances (e.g. lawnmowers, generators, and racecars) to stop working. That’s why for boats, outboard motors’ winterizing helps ensure it would run smoothly when you use them again.

  • Another time fogging becomes necessary is when storing your boat for a long time. Again, lack of use may lead to difficulties in making the motor work. This may be caused by rust or corrosion across the boat’s parts.

How to Fog an Engine: Step-by-step Process

Before starting any DIY project, check what kind of motor your boat has. It determines what type of fogging you need to execute. Here are the two major types:

1. Four-stroke Engines


Unlike two-stroke engines, given its recent developments, four-stroke types don’t necessitate fogging. This is because they were manufactured such that their gas and oil act as a lubricant.

However, it is strongly recommended to fog them to ensure you don’t encounter problems in the future.

Fogging doesn’t require expertise or too much mechanical skills anyway. You can finish it in a few minutes.

  1. Start up the engine and pour the fogging oil into the engine’s air intake. Doing so places the engine at its operating temperature. Since it is warm, the oil easily and smoothly spreads throughout the parts versus doing it in cold, dry air.
  2. Make sure you coat the cylinders, too. But remember to turn off the engine first and remove the spark plugs before doing so.
  3. Place them back after you have turned the engine a bit (use a ratchet or a similar tool) to ensure proper coverage.

2. Two-stroke Engines


This type of engine is older than its four-stroke counterparts. Rather than fuel-injected, it is carbureted. For those unfamiliar, carbureted engines are weaker than high-performing and economical fuel-injected engines.

However, some people still swear by carbureted as it is easy to clean and rebuild.

  1. If your boat has a 2-stroke outboard motor, connect outboard muffs and flush out the water first before starting the engine.
  2. Afterward, spray the fogging oil across the carburetor. The engine may sputter a bit and will blow smoke. But you don’t need to panic. Simply wait for it to cut out before turning it off completely.
  3. Afterward, you can now safely store an outboard motor for the winter.

Now, you may ask, “How to go on about fogging an inboard boat engine?” You can repeat the steps for Four-stroke engines.

But make sure to do the following as well:

  • Remove water from the engine, drain plugs, hoses, and heaters
  • Thoroughly clean your boat
  • Repair any damages, especially on the propeller
  • Take out the battery

As for fogging outboard motor, drain the carbureted engines of gas and water. Similarly, clean your boat and remove the battery before storing the boat for winter.

Alternatives to Fogging


If you are on a tight budget or you simply want to use an existing product in your home, here are some alternatives to fogging oil.

1. Use Lubricant

Cheap for its multipurpose use, a generic lubricant can do the job of ‘oiling’ your engine. However, it remains weaker compared to fogging oil. The latter is formulated to ensure the longevity and the quality of the boat’s internal parts.

2. Mix 2-cycle oil with regular fuel

For the homemade mixture, make sure to use 1 part of oil and 9 parts of fuel. Be precise in your measurements before blending the two types of fuel to ensure you can imitate the properties of a fogging oil.

Frequently Asked Questions

Is fogging oil expensive?

Compared to bringing your boat to repair shops or its manufacturer, protecting it from corrosion is much less expensive. For example, a 12 oz fogging oil costs $14.97, while a high-performance one costs $26. Remember, you can also use it for other appliances so it is worth your purchase.

Can a fogging oil damage the engine?

A fogging oil has properties that are safe for a boat’s internal parts, like the engine or motor. These are usually sensitive, so the fogging oil is formulated to be compatible with them.

In case you do notice a strange chemical reaction, stop spraying right away. Check how you can repair the damage and use a different brand or type of fogging oil instead.


As winter season approaches and you need to store your boat, you may hear boat veterans advising you to fog it. You may ask, “Is fogging a boat motor necessary?” Yes, as the special oil acts as a protective layer to your boat’s most important part: the motor.

Keep in mind it is better to spend a little more on your boat. After all, it is your investment, and you want to keep it working in the long term so you can enjoy your day cruising and watersports.

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