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

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

As the weather gets colder, boating occurs less and less frequently, which means more owners are winterizing their boat engines. But how do you protect your engine during long-term or winter storage? Fogging your boat engine is an excellent solution to protect and extend your engine’s life. 

Keep reading to learn more about engine fogging and how to fog your outboard motor.

What Does It Mean to Fog an Outboard Boat Motor?

Fogging a boat engine is an essential part of the winterizing process. If you’re putting your boat into long-term storage, fogging the outboard motor is vital.  

Engine Fogging for Long Term or Winter Storage (Outboard Boat) - Tips from Tom

Fogging oil is a waxy oil that you spray into your engine to essentially coat its components and protect them from corrosion while it’s sitting. You’ll spray it into the carburetors and spark plugs (carefully) so that the oil can coat every part of the motor.

Your motor will be running during this process, so we recommend using a good stabilizing fuel additive and treading carefully. 

How Does Fogging Oil Work?

According to Gold Eagle Co., an automotive fluid company, fogging oil is an “aerosol petroleum treatment for long-term lubrication and corrosion resistance.”

Essentially, the fogging oil coats the inside of the engine with a film that will remain while the engine is stored long-term. 

STA-BIL (22001) Fogging Oil - Stops Corrosion In...
  • Coats internal engine components to prevent corrosion
  • Displaces moisture from metal to protect engine
  • Lubricates cylinders to prevent cylinder damage (scuffing) at...

Did You Know: Believe it or not You Can Turn Any Motorhome Into a Houseboat, But Should You? Find out!

What Are the Benefits of Fogging a Boat Engine?

The main benefit of fogging a boat engine is to prevent the engine’s inner walls from rusting. Regular oil or gasoline frequently contains impurities and water, which can damage your engine when stored. 

Outboard Motor
If not properly maintained, outboard motors will rust rather quickly.

Also, these liquids cannot coat the engine walls, so the contaminants, water, and air inside the motor can corrode the exposed metal. Because fogging oil adheres to the engine walls and stays there for the entirety of storage, it prevents corrosion while the engine remains idle.

If you’ll be storing your boat long-term, fogging the engine is always a good idea. It’s affordable and easy to do, so why wouldn’t you take the precautions? 

Note: Fogging oil should not be used on diesel engines.

How to Prepare an Outboard Boat for Long-Term Storage

Fogging your boat engine is a good option for long-term storage, but some necessary steps ensure it’s successful.

Outboard motor covered in ice
This is a good example of why people store their boats in the winter.

Additionally, fogging a boat engine can be a DIY job, but if you don’t feel comfortable with the job, you should take your engine to a small motor mechanic. So, let’s look at each step to make sure you can successfully fog your engine.

Stabilize the Fuel System 

First, you must stabilize your fuel by adding products such as STAB-IL’s Storage Fuel Stabilizer or Biobor’s EB Ethanol Treatment for Gasoline. These products keep gum and varnish from forming in the gasoline and gumming up the engine. 

STA-BIL Storage Fuel Stabilizer - Keeps Fuel Fresh...
  • STORAGE – STA-BIL Storage Fuel Stabilizer eliminates the need...
  • ENSURES QUICK, EASY STARTS – Treating your gas with this fuel...
  • VERSATILE – STA-BIL Storage Fuel Stabilizer is safe for use in...

Then, following the manufacturer’s instructions, mix the appropriate amount into the oil and cycle it through the system.

Spray Fogging Oil Through the Running Boat Engine

Spraying fogging oil through the running boat engine is usually a job for outboards with electric fuel injection (EFI). In this method, you’ll add fogging oil directly to the gasoline running through the entire engine. 

Fogging outboard boat engine with EFI
For outboard motors with electric fuel injection, you’ll add fogging oil directly to the gasoline.

After adding the gas and oil combination, run the engine until white smoke emits. Often, this will cause your engine to stall and shut off; if it doesn’t, shut off the engine as soon as you finish spraying. 

Avoid fogging oil created for carbureted engines. This carburetor fogging oil has a wax-like additive that can clog the fuel lines of an EFI motor. 

Spray Fogging Oil Directly into the Cylinders 

For carbureted engines, the fogging oil should run directly into the cylinders. Spray a healthy amount of fogging oil into the carburetor while the engine is running, and then disconnect the motor from the fuel supply. 

Removing boat engine spark plugs
When fogging carbureted engines, you’ll want to remove the spark plugs and spray the fogging oil into the cylinders.

Then, continue to run the engine and spray fogging oil until all the gas in the carburetor burns up, and the engine dies. The outboard should sputter and emit white smoke before it stops, which is normal and of no concern.

If it doesn’t automatically stall your motor, shut it off immediately after you’re done spraying.

Check for Water Contamination in the Gear Oil Lower Unit on Outboards and Outdrives 

Before you finish fogging your boat engine, you’ll also need to check the gear oil in the lower unit of your outboard motor for potential water contamination. Water in the gear oil can be a concern and cause more problems because it can condense inside the tank and corrode the engine. Therefore, you should drain the oil and replace it with the lubricant your owner’s manual specifies. 

Boat engine oil
Replace contaminated oil to prevent engine corrosion.

Replace Your Oil If Needed

Before you finish, you must replace old or contaminated oil and fill the oil reserves completely. A full oil tank will stop water from condensing inside the tank and contaminating the oil supply.

Charge and Disconnect Your Battery

Charge and disconnect your battery before any long-term storage, which will help keep it charged and ready to use in the future. 

Did you know? RVs often have a battery disconnect switch that allows you to easily disconnect the batteries without having to remove cables. These switches can also be installed on boats.

battery terminal
Disconnecting your battery before storage will help maximize its lifespan.

Additionally, store it in a location that doesn’t have significant temperature shifts. A place that’s too hot or cold can be detrimental to your battery health.

Drain Gas from Carburetors if Your Engine Is Carbureted

If your engine is carbureted, you’ll need to drain the gas from the carburetor. Any gas left in it prevents varnish deposits from the stagnant gasoline from forming. Therefore, removing the excess gas and fogging the engine will reduce the varnish deposits and ensure your boat will start when you take it out of storage.

Is Fogging a Boat Engine Necessary?

Fogging a boat engine is not completely necessary but is highly recommended. Putting a stabilizer in your gasoline can help reduce the long-term storage issues but is not a guarantee. Essentially, fogging oil is an inexpensive way to better protect your boat engine while it’s left idle.

Replacing an outboard motor is a lot more expensive and time-consuming than fogging one.

While your boat’s in winter storage, head south and hop aboard one of the 9 Best Naples, Florida, Boat Tours for Cruising the Coastline.

Are There Alternatives to Fogging Oil?

There are some alternatives to fogging oil. Some people suggest using WD-40 or penetrating oil. However, none of these other methods have been proven. Some experts say they’ve used acceptable alternatives successfully while others have had motor-killing problems.

Others refuse to try anything but fogging oil on their outboard motor because it simply isn’t worth the risk. You’ll need to research alternatives and decide for yourself which is the best option for your boat.

Save Your Boat Engine with Fogging Oil 

Winterizing or preparing your outboard motor for long-term storage is a beneficial process. And, fogging a boat engine can be a simple and inexpensive solution to the potential problems that may arise while storing your boat long-term. Ultimately, using fogging oil can be the difference between a well-working engine or a corroded one after months of sitting idle.

RV pulling a boat
Before you put your boat in storage, protect your outboard motor by taking the time to fog it.

If you’ll be storing your RV as well, there are steps you need to take to protect the interior and exterior components of your rig. Learn more here: How to Store Your RV

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Wednesday 16th of November 2022

But what if you have an engine with MPI fuel injectors. It is my understanding that you don't want to fog these using the method that you described. Furthermore, what if the boat is stored in the water as well. Any suggestions?


Friday 22nd of April 2022

Thank you. I’m a beginner. This is very helpful because the manual is not always useful. It’s better to watch the process. If it’s not “see Jane catch the ball, it’s too complicated!?