How to Winterize Your Mercury FourStroke Outboard

[@KevinRichardson-m3x]

So many different videos on this with lots of different information. After reading my manual and watching this video I like your video. Nice Job!

[@bennyserrano440]

Thank you for getting back to me. Greatly appreciate it.🎸

[@bennyserrano440]

Great info, greatly appreciated... quick question I have a Mercury Outboard and im in the Northeast.. Should I run marine antifreeze thru it as well?

[@QuicksilverProducts]

Mercury outboard engines are self-draining. This means all water from within the engine drains out when the engine is not running and in the trimmed down position. Mercury does not recommend the use of antifreeze in the cooling system of their outboard engines as it could have damaging long-term affects to the cooling system coatings and seals.

[@davidmclaughlin5345]

By design is there water cooling of the lower crankcase oil sump? When I water test my 2024 Mercury Pro XS 150 with muffs there is a small amount of water pulsing out the oil drain port? Is this normal?

[@URUTUMNAGO]

What are the torque specs for the propeller nut? I noticed in the video a torque wrench is being used.

[@fallbranch4349]

When cranking the engine to distribute the fogging oil do you need to run water through the engine to prevent damage to the water pump?

[@QuicksilverProducts]

Because the engine cranks so briefly, water in the water pump is not necessary.

[@Maynardd]

No, because you’re not running the engine

[@timhayden818]

awesome 👏 thank you

[@georgek9231]

great video when you put fuel stabilizer in, are you able to run your engine for 5 min with no water in the engine? just want to make sure thanks

[@QuicksilverProducts]

We're glad you asked. You must never run your outboard engine without a source of cooling water. Even running the engine for less than 30 seconds without a water source can quickly destroy your water pump, leaving you with more work to do than you originally anticipated. Check your operator's manual for flushing instructions for the product you own. Some outboards have a flush system built-in and the engine can be running while flushing, while other models will require an attachment.

[@johnfarmer4099]

Seems like a relevant question!

[@jeffwhiting6949]

@@QuicksilverProducts can we add the fuel treatment to the boat while its still in the water before we pull it out and run it in the water so we dont need to worry about the water source ?

[@roberthuntingtonsidell3945]

I am primarily concerned about water freezing in the outboard over the winter. I did my best to drain the water when taking the boat out of the water. Is there anything I should specifically do to protect against freezing?

[@QuicksilverProducts]

Hi Robert, great question. As long as the engine has been placed in the vertical position after being pulled from the water (trimmed all the way down), the water within will have drained by itself.

[@80694824]

Hi, great video. I used to live in FL but now southern TN. I plan on keeping my boat in a wet slip, do you have a video or process for people keeping boats in water? I can’t get my engine vertical to drain all the water without it being in the water. The rest of the steps I understand.

[@QuicksilverProducts]

Engines kept in a wet slip will automatically drain all of the water from the powerhead and cooling system upon shutting off. Water will only remain in the outboard from the waterline down.

[@fengbeer]

Great video. Thank you so much. How do you run engine for 5 minutes without damaging the engine while boat is out of water?

[@davidwalder290]

They sell these suction cup looking things that attached to a hose, I think they are called earmuffs. They go over the water intake and you can run water through the engine and run it without damage.

[@QuicksilverProducts]

As noted by another member here, freshwater flush muffs of several sizes are available through various marine retailers near you. The attach to the lower unit of the outboard and cover the water intakes, while a hose attaches to the muffs supplying cooling water. Install the muffs, turn the water on and start the engine. Removal is the reverse of those steps.

[@Wizzle87]

Is there any trick to getting fogging oil in cylinder 4, i cant find a longer straw and the fogging oil doesnt spray upside down

[@castmastersoutdoors7762]

I recently did all this about a month ago so basically my engines already winterized what about the water in the intake how do you flush that out

[@QuicksilverProducts]

Outboard engines are self-draining, meaning that when they are placed in the vertical position, the cooling system will drain out the intake holes. You want to store the engine in as close to a vertical position as possible, especially if being stored outdoors where water could accumulate in the cavity of the lower unit. Great question!

[@georgek9231]

I live in new York. I noticed you didn't use antifreeze to winterize/ Is that something you recommend and do you have a video on that? Thanks

[@QuicksilverProducts]

Great question! Mercury Marine outboards are self-draining. Once the engine has been pulled from the water, they simply recommend flushing it with fresh water and placing the outboard in the operating position (vertical) so the water drains out. Quick and easy. 😊

[@georgek9231]

@@QuicksilverProducts thank you so much. Would you recommend bottom painting a new boat that is left in the salt water for the summer months? or can I pull it out of the water every 2 weeks to clean and wax the bottom with out bottom painting. Thank you so much

[@QuicksilverProducts]

There are certainly pros and cons to both sides of that coin. There are also variables at play, and it's not exactly our area of expertise. We recommend chatting with local marinas and slip owners in your particular area. In some waterways, people can get by with minimal cleaning or maintenance throughout the season. In other waterways, they're brushing and cleaning their hulls almost weekly. It really depends. Local feedback specific to your conditions will be your best bet here.

[@georgek9231]

@@QuicksilverProducts thanks alot

[@JetDriver1111]

@@georgek9231 you can pull it and clean it….but it’s a lot off work !

[@mmalamute5472]

How cold is the Leg/gear oil good for? Other engine manufactures have suggested leaving gear oil empty for winter to avoid freezing in gear case.

[@QuicksilverProducts]

Quicksilver gear lubes are completely safe for winter storage in cold climates. While the gear lube will not freeze, any water that has found its way into the gear case will separate from the lube and freeze/expand, which can cause damage. Draining and replacing your gear lube right before storage ensures that any water that has made it's way into your lower unit during seasonal operation has been removed.

[@machinistsunion6384]

For bottom end gear oil change the oil seals on the vent plug and drain plug should be replaced every time - correct? What about the "lock" on the shaft nut, add anti seize to the spline and there is also a large plastic washer/spacer behind the prop up to the lower housing.

[@QuicksilverProducts]

Correct - drain and vent seals should be replaced during each service to avoid water intrusion of your gear housing assembly. Locking propeller nuts and the hardware associated can be reused throughout the season, but these components should be inspected each year or every 100 hours of use. During this inspection we also recommend a light coating of 2-4-C grease to the spines of the propeller shaft.

[@stevek8833]

Doesn’t fogging the engine greatly increase the likelihood that the spark plugs will need to be replaced?

[@QuicksilverProducts]

Not necessarily. When the appropriate amount of engine oil or storage seal is used to coat the cylinder walls, the spark plugs should not need to be replaced upon recommissioning.

[@stevek8833]

@@QuicksilverProducts thanks! I have a 175 pro XS 4stroke and when I cranked my engine for about 5 seconds with the spark plugs removed and fogging oil in, it didn’t sound anything like the video. it didn’t sound like it was trying to start like in your video. Is that normal?

[@QuicksilverProducts]

Keep in mind that the sound of the engine cranking in our video has been reduced, so the cranking sound would not overtake the video. The engine in this video is also an inline four-cylinder, whereas you have a V6, so they will sound different. If you're concerned that something may not be quite right with your engine or how you prepared it for storage, we encourage you to connect with Mercury Marine product support for advice. You can reach them by visiting www.mercurymarine.com/en/us/contact. We hope this helps!

[@stevek8833]

@@QuicksilverProducts thanks for being so responsive! I really appreciate it!

[@zacharybava186]

The instructions on that specific can say to spray into the air intake to stall the engine, I sprayed directly into cylinders and cranked engine (like in the video) per my engine manual instructions. I live in the Midwest where it gets cold, will the other components of my engine be okay? Thanks

[@QuicksilverProducts]

Great question, and the answer is yes. If you've pulled the spark plugs and sprayed Storage Seal into the cylinders, you're all set.

[@stilltuckered]

Is there a ‘water separator’/‘moisture separator’ that needs winter servicing?

[@QuicksilverProducts]

This depends on the engine model. Some engines have a water-separating fuel filter that should be emptied or changed, while others simply have general fuel filters that remove debris in the fuel. We recommend checking the operator's manual for the engine you own for detailed instructions on winter storage preparation. Depending on the boat, you may also have a remote water-separating fuel filter between the fuel tank and the engine. Be sure to review the manual for each to be sure.

[@JetDriver1111]

What keeps the ignition system from getting damaged while cranking it over with the plugs out ? This is usually a big no no ! That is why we ground the plugs while they are out so the energy has somewhere to go !

[@Maynardd]

Why would you think the ignition system would get damaged. That’s like saying you’re going to damage your ignition system when starting the engine.

[@JetDriver1111]

@@Maynardd the energy in the ignition coils needs to go some where..

[@Maynardd]

@ this is what any mechanic will tell you to do.

[@johndelgrosso2699]

I have a 2022 Mercury Pro XS 115. I’ve read that I should run 2 cycle oil through motor until it smokes . Is this ok to do? 3 oz to one gallon.

[@QuicksilverProducts]

Great question! We do not recommend using a 2-stroke oil and fuel mixture in your 115hp ProXS. The fuel systems on newer FourStroke engines are complex, and running mixed oil/fuel through them would mean that mixture stays in the fuel injection system throughout the winter and can have a negative impact on pumps, injectors, etc. We recommend removing the spark plugs and spraying Storage Seal into the cylinders as noted in the engine operation and maintenance manual.

[@johndelgrosso2699]

@@QuicksilverProducts I called Mercury today, they said to fog the cylinders with Merc fog spray. Or use the 10/30 oil from motor . A cap full in each cylinder. I’m going to just use fog .

[@QuicksilverProducts]

Perfect; thank you for circling back with us. The "fog" that Mercury recommends is called Storage Seal Rust Inhibitor. The same formula is offered from both Mercury Marine and Quicksilver Products. Mercury-branded products you'll only find through authorized Mercury Marine dealers. Quicksilver Products can be found through various automotive and big box retailers, as well as through our Amazon store.

[@pkg2922]

Does rotating your engine with the starter also rotate the impeller to the point of creating enough friction to possibly damage it? Clearly the motor won't fire up without spark plugs and will only be turned over by the starter, so presumably it would not rotate fast enough for that to happen, but wanted to confirm if my assumption is correct and if there is anything to watch out for? Like flooding the cylinder? Can it be turned over by hand?

[@QuicksilverProducts]

Bumping the key to turn the engine over should not be enough to damage your water pump impeller. Turning the engine over by hand is also an option and can usually be done with a breaker bar and a socket on most models. On many fuel injected engines, the operator's manual may also suggest disconnecting the electrical harness going to the fuel pump or removing a fuse so it does not operate. Be sure to check the manual for the product you own to be sure.

[@pkg2922]

@@QuicksilverProducts super clear, thank you so much

[@Hardcase19691]

Do you recommend all of these steps if the boat is stored in a heated garage? Also, after fogging the engines are you putting the original spark plugs back in or new spark plugs? thanks

[@QuicksilverProducts]

The same steps apply to engines stored indoors as well as outdoors. Since spark plugs only need to be changed every 300 hours or every 3 years in most cases, there will be situations where the plugs are reused. Great questions!

[@NenXKicks]

Do i have to fog my 2025 mercury 90hp EFI 4stroke? I heard that can damage sensors

[@QuicksilverProducts]

Mercury Marine provides an operators manual with each engine they sell. Storage preparation can vary by engine model, so we recommend checking the manual provided with your engine to be sure of the steps. If you need assistance or do not have a manual, we recommend reaching out to Mercury Marine product support by calling 920-929-5040. Thank you!

[@crazyheart1976]

What does this usually cost if you don't want to mess with it and want to take it to the dealer???

[@QuicksilverProducts]

Hello David, that is a great question. Pricing for winterization services can vary by dealership and region, so we encourage you to contact a few dealers near you to discuss. If you own a Mercury Marine outboard, you can visit www.mercurymarine.com/en/us/find-a-dealer/ to get started. Other manufacturers likely have Dealer Locator functionality on their websites as well. We hope this helps!

[@jbone1982wi]

First year I had my outboard I took it to a local marine mechanic and they charged about $350. Cheaper and easy to do it yourself

[@dayedanny7941]

NICE JOB BUT ARE WE FORGETTING TO ADD SOME ANTIFREEZE TO THE ENGINE FOR WINTER OUTDOOR STORGE .

[@QuicksilverProducts]

Hi @dayedanny7941! Mercury Marine outboard engines are self-draining. This means that when you remove the flush attachment, all cooling water from within the engine drains out. Mercury Marine does not recommend the use of antifreeze or anything other than water in their outboard engine cooling systems at any time.

[@peretjim4377]

Wish I had a Mercury instead of an oddball Suzuki. Merc seems easier to winterize.

[@kevencornett939]

Couple dealers told me no fogging

[@QuicksilverProducts]

Great question/comment. Winterization steps will vary by engine brand and model. This video was created when following the steps laid out in the Mercury Marine operator's manual for this particular engine, and we encourage all users to follow the steps in the manuals supplied with the engines they own.

[@kmeals9898]

You're misinforming people, you don't fog 4 cycle engine, only 2 strokes.

[@QuicksilverProducts]

The steps taken in this video are aligned with what is written in the service materials provided by Mercury Marine.

[@jjstierman]

Everything I've read plus even Google says you still fog 4 strokes. Who told you otherwise?

[@_STNML]

Wrong lol

[@jarettgustafson3611]

From what I've heard sometimes sensors can be damaged on certain engines with fogging oil in 4 strokes. I haven't seen it personally yet but each engine is different. There is a 4 stroke fogging oil that you can add to a cruiser day and then run the engine off that for 5 to ten minutes from yamaha, I've used plenty of times

[@billiebob2363]

Talked with Mercury Outboards home office today regarding my 150 Pro XS Four Stroke. Fog it!