Mercury Outboard Fuel Additives & Fogging Oils

Mercury Marine Engine Lubricants, Oils, and Additives Resources and Information

PartsVu.com is happy to offer a wide selection of certified Mercury outboard lubricants, oils, and additives to match the exact specifications of your Mercury outboard engine. If you need assistance servicing your Mercury outboard, follow along with these helpful guides over on our blog: Mercury fuel system 100-hour service, Guide to Mercury Marine Precision Oils and Lubricants.

Browse the rest of our complete selection of Mercury outboard parts, or shop our list of Mercury lubes, oils, and additives categories, including: 

• Mercury Precision Lubricants Engine Oil
• Mercury Marine Gear Lube & Power Trim Fluid
• Mercury Corrosion Inhibitors & Grease
• Mercury Marine Fuel Additives & Fogging Oils
• Quicksilver Marine Engine Oil
• Quicksilver Marine Fuel Additives & Fogging Oil

We also offer helpful resources to help you maintain your Mercury outboard motor, such as:

• Mercury Outboard Service Schedule
• Mercury Outboard Specs & Capacities Chart
• Mercury Outboard 100-hour Service Guides

Mercury Outboard Lubricants, Oils FAQs

How do I change my Mercury 4-stroke outboard engine oil?

As the old oil is draining, you can work on removing the engine oil filter. Depending on your specific Mercury model, your filter may have a drain lip that helps to keep the mess to a minimum when you unscrew the old filter. However, most older engines do not have this feature. We suggest being prepared with plenty of absorbent rags or placing a small cup that is cut to size below the filter before removal. Using a PartsVu Maintenance Essentials filter wrench is the best way to loosen the filter. Remember when you reinstall the filter, over-tightening will only make your life more difficult when you are ready for the next service. Some technicians puncture the old filter allowing trapped oil to drain back into the block before removal, but this will ruin your ability to take the filter apart for further inspection.

Several laboratories provide performance testing of used oils, allowing you to learn more about the health of your engine. Blackstone Labs is one such provider, and they have a convenient mail-in kit that includes everything you need to submit an oil sample. They can also test gear oils, hydraulic fluids, and oils from your other vehicles or toys. Oil test results can tip you off to an accelerated wear condition inside of your engine long before any other symptoms show up. If you still want to know more about your engine, purchase an oil filter cutter and open the spent filter to look for evidence of contamination and metal dust or shavings.

Once you have inspected your spent oil and filter, set them aside for proper disposal. If you removed the drain screw to empty your oil, carefully reinstall the drain plug. The new oil filter should be removed from its package and the o-ring lubricated with a thin coat of fresh engine oil. Spin on the new oil filter and gently tighten to seat the o-ring without over-torquing.

Mercury Marine offers a wide assortment of engine oil – both in blend and viscosity. If you are uncertain as to which oil is best for your application, consult your owners’ manual. Loosen the yellow oil fill plug on the top of the engine and pour in fresh oil. We recommend adding slightly less than the stated capacity. With the engine trimmed down, check the oil level on the dipstick after allowing a few minutes for the oil to drain into the oil pan properly. Filling the oil to the lower level on the dipstick will help you to measure if the oil level changes over time with the engine in operation.

Why should I use Mercury fuel additives?

Quickare treats and stabilizes fuel at every fill-up which is necessary because just about all gasoline today contains up to 10% ethanol. Left untreated, ethanol-blended fuel can break down leading to gum and varnish build-up which causes internal engine corrosion. Fuel additives such as a bottle of Quickare keep fuel fresh between fill-ups for up to three months.

The second step within Mercury’s fuel care system cleans your engine and fuel system. All combustion motors develop carbon deposits and the best way to clean those deposits is to add Mercury Quickleen to your fuel tank. Simply add a bottle of Quickleen to your outboard fuel tank once per year to remove carbon deposits, prevent engine knocking, piston seize up, and extend spark plug life. Aggressive fuel system cleaner within Quickleen works to quickly and thoroughly remove carbon deposits from carburetors and fuel injectors, intake valves, spark plugs, piston crowns, and cylinder heads.

Likely, there are periods when your boat is stored or is used infrequently, which can lead to issues with your engine running. If your boat will be sitting for an extended period of time, you need to add a fuel stabilizer like Mercury Marine Quikstor to prevent both regular and ethanol-blended fuels from breaking down, oxidizing, and causing fuel system corrosion, and eventually affecting the engine’s performance. Before storage add a bottle of Quickstor to your fuel tank, then run the engine so that the treated fuel circulates throughout the engine and fuel lines. This extended fuel stabilizer prevents gum and varnish from forming in the engine, fuel lines, and tank and stabilizes fuel for up to one year, thereby successfully averting any fuel-related problems. One ounce of Quickstor treats five gallons of fuel, so a 12-ounce bottle treats 60 gallons.

How do I service my Mercury 2-stroke outboard motor grease points?

Note that fittings can be contaminated by salt – especially the ones near the steering tube – so replace them if they are too corroded to accept grease. Watch as you pump fresh grease into the fitting and see if old, dirty grease or water or both push out from the corresponding space. Ideally, these cavities are filled with clean grease all the time. A light coating of grease on the tip of the trim rams will reduce friction there as well. If your engine is equipped with stainless balls on the tips of the trim rams, work the balls to get the grease inside their cup.

If your prop was not removed for the gear lube change, remove the cotter pin or lock washer from the propeller and loosen the prop nut. Exercise extreme caution as prop blades can be very sharp. With the nut loosened, remove the propeller and associated prop hardware to inspect the propeller shaft.

Look for fishing line that may be behind the prop and near the prop shaft oil seals. Remove any line and if the seals are intact, apply a fresh coating of Mercury 2-4-C grease to the propeller shaft before reinstalling the prop. Tighten and use a new cotter pin to complete the installation if applicable.

Be aware that your boat’s propeller functions like your vehicle’s tires. Wear on the edges of the propeller can reduce traction, causing speed and fuel efficiency loss. Propeller reconditioning or replacement should be considered if you note wear, rounded edges, thin blades, or cracking. You should also inspect, and replace as needed, the hub inside the propeller. Cracking or wobbling can indicate a worn or damaged hub.

This is also a great time to inspect your external engine anodes. Anodes worn beyond 50 percent should be replaced. Be sure to select the correct sacrificial alloy. The proper sacrificial alloy will depend on whether you boat in salt or freshwater. Spend an extra couple of minutes to check fitment because different propeller selections will not work with all anodes.

On the powerhead itself, corrosion inhibitor can be liberally applied to the metal surfaces, taking some care to avoid the air intake itself. We recommend Boeshield’s T-9 brand, but any high-quality marine corrosion inhibitor will help. If any salt residue exists on the engine, rinse with a light stream of fresh water before applying T-9. This product also works well on battery connections, fuel/water separator bases, and trailer parts.

If you have exposed metal surfaces on your lower unit, trim assembly, steering tiller arm, or trim motor itself, consider purchasing a can of Mercury’s Corrosion Guard to supplement paint on these surfaces.

How do I remove Mercury fogging oil from my engine?

To remove Mercury fogging oil from your engine, follow these steps:

1. Start by running your engine in a well-ventilated area for a few minutes to help burn off any excess fogging oil. This will also help to warm up the engine, which will make the removal process more effective.
2. Once the engine is warmed up, turn it off and disconnect the fuel line to prevent any fuel from entering the engine.
3. Next, remove the spark plugs from the engine and spray a small amount of carburetor cleaner or brake cleaner into each cylinder. Use a rag or paper towel to wipe away any excess cleaner and oil that may have accumulated.
4. Reinstall the spark plugs and reconnect the fuel line.
5. Finally, start the engine again and let it run for a few minutes to help burn off any remaining fogging oil. Monitor the engine carefully during this time to ensure that it's running smoothly and that there are no signs of damage or other problems.

It's important to note that fogging oil is designed to help protect your engine during storage or periods of extended non-use, and it should not be used as a substitute for proper maintenance and care. Always follow the manufacturer's recommendations and guidelines for engine maintenance and use, and consult a qualified mechanic if you have any questions or concerns about your engine's performance or maintenance requirements.

How to clean fuel injectors on Mercury outboard?

Cleaning the fuel injectors on a Mercury outboard is an important maintenance task that should be performed regularly to keep your engine running smoothly. Here's a step-by-step guide on how to clean fuel injectors on a Mercury outboard:

• Disconnect the battery: Before beginning any maintenance on your boat's engine, always disconnect the battery to prevent accidental starting.
• Remove the fuel injectors: Carefully remove the fuel injectors from the engine block, taking care not to damage any components.
• Inspect the injectors: Inspect the injectors for any signs of damage or wear. If the injectors are damaged, they may need to be replaced.
• Soak the injectors: Place the fuel injectors in a container of fuel injector cleaner or a mixture of gasoline and a fuel system cleaner. Follow the manufacturer's instructions on the amount of cleaner to use and the length of time to soak the injectors.
• Clean the injectors: After soaking, use a soft-bristled brush to clean the outside of the injectors. Use compressed air to blow out any debris that may be clogging the injector nozzles.
• Reinstall the injectors: Once the injectors are clean and dry, reinstall them in the engine block in their original positions.
• Reconnect the battery: Reconnect the battery and start the engine to test the fuel injectors.

Cleaning your Mercury outboard fuel injectors is an essential maintenance task that should be performed regularly. It can help improve engine performance and prevent costly repairs down the road. If you're unsure about cleaning your fuel injectors, consult your Mercury dealer or a qualified marine mechanic.

What is the best fuel additive for gas engines?

When it comes to choosing a fuel additive for your Mercury outboard engine, it's important to select a product that is specifically designed for use in marine engines. The best fuel additives for Mercury outboards are those that can help improve engine performance, reduce emissions, and protect against fuel system corrosion.

One popular option for Mercury outboard engines is Sea Foam Marine PRO, which is designed to clean and lubricate fuel systems, stabilize fuel, and reduce emissions. This product can help keep your engine running smoothly and prevent costly repairs down the line.

Another good option is Star Tron Enzyme Fuel Treatment, which uses enzyme technology to break down and eliminate harmful deposits in fuel systems. This product can help improve fuel efficiency, reduce emissions, and extend the life of your engine.

Where can I find Mercury Verado outboard fuel additive for sale when I'm on a trip?

If you're on a trip and need to find Mercury Verado outboard fuel additive for sale, there are a few options to consider:

Local Marine Supply Stores:

1. Check with local marine supply stores in the area where you're staying. They may carry Mercury Verado outboard fuel additive or be able to order it for you.

Boating and Fishing Stores:

1. You can also check boating and fishing stores in the area. They may carry the fuel additive or be able to point you in the right direction.

Online Retailers:

1. If you have access to the internet, you can search for the fuel additive on online retailers such as Amazon or eBay. Many retailers offer expedited shipping options to ensure that the product arrives quickly.

Mercury Marine Dealers:

1. Check with nearby Mercury Marine dealers. They may carry the fuel additive in stock or be able to order it for you. You can use the "Find a Dealer" tool on the Mercury Marine website to locate a dealer near your location.

Remember to check the availability and pricing of the product before making a purchase, and don't forget to factor in shipping costs and delivery time.

Where can I learn more about Mercury outboard parts and Mercury outboard additives?

PartsVu understands that boaters want to learn how to perform their own Mercury outboard maintenance. From maintaining your Mercury outboard, Mercury sterndrive, and MerCruiser engines, there’s always something new to learn and save money. That’s why PartsVu offers our comprehensive blog, The Partsvu Xchange. 

Read up on the latest developments in boating, as well as search for everything you need to know about Mercury outboard maintenance.

To get you off to a good start, these are some of the most important articles on best fuel additive for Mercury outboards, how much gas treatment to use, and more:

• Winterizing Mercury Outboard Motor
• Mercury Fuel System – 4-Stroke 100-Hour Service
• Mercury Outboard Season Breakout
• Ethanol Gasoline in Outboard Engines

How to fog a Mercury 4 stroke outboard?

Fogging your Mercury 4-stroke outboard engine is an important step to protect it during storage or off-season periods. Here are the general steps to fog a Mercury 4-stroke outboard engine:

1. Start the engine and let it run for a few minutes to warm up.
2. Turn off the fuel supply or disconnect the fuel line to stop the engine from receiving fuel.
3. Remove the spark plugs from the engine. You may want to label them to ensure they go back into the correct cylinder.
4. Attach a fogging oil spray nozzle to the can of fogging oil and insert it into the spark plug hole of each cylinder one at a time.
5. Spray a short burst of fogging oil into the cylinder until it starts to smoke heavily.
6. Turn the flywheel by hand to distribute the oil and repeat the process for each cylinder.
7. Reinstall the spark plugs and torque them to the manufacturer's specifications.
8. Run the engine for a few seconds to ensure the fogging oil is distributed throughout the engine.
9. Turn off the engine and reinstall any components you removed during the process.

Note: Always follow the manufacturer's instructions when using fogging oil and wear appropriate personal protective equipment such as gloves and eye protection.

What does fuel stabilizer do?

Fuel stabilizer is a chemical additive that is designed to help prevent gasoline from degrading over time. When gasoline sits unused in a fuel tank or container for a long period, it can break down and form gum and varnish-like substances that can clog fuel lines, carburetors, and injectors.

Fuel stabilizer works by slowing down the oxidation and evaporation of gasoline. It does this by inhibiting the formation of varnish and gum, which can cause fuel system components to malfunction. It also helps to keep fuel fresh and combustible, so it's easier to start engines after long periods of storage.

Fuel stabilizer is particularly useful for boaters who store their boats and engines during the off-season or for long periods. By adding fuel stabilizer to the fuel tank before storage, you can help to ensure that your engine will start easily and run smoothly when you're ready to use it again.

Note: Always follow the manufacturer's instructions when using fuel stabilizer, and use the recommended amount of stabilizer for the amount of fuel you're treating.

Can you put fuel stabilizer in a 2 stroke Mercury outboard engine?

Yes, you can put fuel stabilizer in a 2-stroke Mercury outboard engine. In fact, using a fuel stabilizer is especially important for 2-stroke engines, as they tend to be more sensitive to fuel degradation than 4-stroke engines.

When gasoline sits unused in a fuel tank for an extended period, it can begin to break down and form gum and varnish-like substances that can clog fuel lines, carburetors, and injectors. Fuel stabilizer can help to prevent this from happening by slowing down the oxidation and evaporation of gasoline.

To use fuel stabilizer in a 2-stroke Mercury outboard engine, simply add the recommended amount of stabilizer to the fuel tank before filling it with gasoline. It's best to use a stabilizer specifically designed for use with 2-stroke engines, as they may contain additional additives that help to protect against the harmful effects of ethanol and other contaminants.

Note: Always follow the manufacturer's instructions when using fuel stabilizer, and use the recommended amount of stabilizer for the amount of fuel you're treating.

Does gas treatment work?

Gas treatment can be effective in improving the performance and reliability of gasoline-powered engines, especially those that sit idle for extended periods. Gas treatment products are designed to improve fuel quality, clean fuel systems, and reduce harmful emissions. They can also help prevent fuel system problems caused by moisture, ethanol, and other contaminants.

When used as directed, gas treatment products can:

• Prevent fuel from breaking down and forming gum and varnish-like deposits that can clog fuel systems
• Clean fuel injectors, carburetors, and intake valves to restore engine performance
• Improve fuel economy by ensuring efficient combustion and reducing fuel consumption
• Protect against rust and corrosion in the fuel system
• Reduce harmful emissions, such as carbon monoxide, nitrogen oxides, and particulate matter

However, it's important to note that not all gas treatment products are created equal, and some may not work as well as others. It's best to choose a reputable brand and follow the manufacturer's instructions for use.

In addition to using gas treatment products, it's also important to use high-quality gasoline and follow the manufacturer's recommended maintenance schedule for your engine. Regularly changing the fuel filter and performing other maintenance tasks can help ensure optimal engine performance and reliability.

How often should you use fuel additives?

The frequency at which you should use fuel additives depends on the type of additive and your specific engine usage. Some fuel additives are designed for continuous use, while others are intended for periodic or seasonal use. It's important to read the manufacturer's instructions for the specific product you're using to determine the recommended frequency of use.

In general, fuel stabilizers and treatments that prevent fuel system problems should be used every time you fill up your gas tank, especially if the fuel is going to sit unused for extended periods. This is particularly important for boats and other seasonal equipment that may not be used for several months at a time.

Other additives, such as fuel system cleaners or octane boosters, may only need to be used periodically or as needed to address specific issues. For example, a fuel system cleaner might be used every 3,000 to 5,000 miles to remove carbon deposits and improve fuel economy, while an octane booster might be used before towing a heavy load or driving in high-altitude conditions.

Ultimately, the frequency of use will depend on the specific additive and your engine usage patterns. Be sure to follow the manufacturer's instructions and use only the recommended amount of additive to avoid potential problems.