Have my 16' alumacraft sitting in the garage right now. I've got a brand new(purchased in april) 25hp yamaha 4 stroke on it. Probably has 20 hours max on it. Being my first 4 stroke, what it proper winterizing technique? Is it much different from a 2 stoke?

Put it in your cellar.

Mix up a heavy dose of 2stroke with gas and run it off that till it runs out (1/2 a gal or so)
Don't fog like typical 2strokes !

West Marine sells "Store & Go", mix in gas, run engine to get through system, turn off. I also flush engine with antifreeze.
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Mix up a heavy dose of 2stroke with gas and run it off that till it runs out (1/2 a gal or so)
Don't fog like typical 2strokes !

a half a gallon or so is way too much running time, it's a four stroke.


I'm with sea dangles, I put mine down the cellar, some years I don't even do that. Had my 97 Honda for 12 years, change the oil, impeller once in a few years and it's fine. I never winterize, just maintenance.

a half a gallon or so is way too much running time, it's a four stroke.


I'm with sea dangles, I put mine down the cellar, some years I don't even do that. Had my 97 Honda for 12 years, change the oil, impeller once in a few years and it's fine. I never winterize, just maintenance.



Per lesson from Monahan's marine.
Run on 2 stroke long enough to get oil through fuel system (5-10 minutes)
Never use fogging oil on a 4 stroke = 1/2 a gal
I overlooked it was a small 25hp, I had a 250

I will tell you what I do Mike and you can take it for what it's worth. I run some gas with stabilizer in it thru the motor. I then change oil and filter and change lower unit lube. I also drain the carbs, you probably have fuel injectors, and take each spark plug out and put a squirt of fogging oil in each cylinder and turn over engine by hand to distribute it. Then put in plugs. I put new plugs in after I have started the engine once in spring. Honda does not recommend fogging engine thru carbs. I take off prop and store motor in down position. Being a smaller engine you can put down cellar. I also have the water pump, thermostat, fuel filter replaced every 2 years. I also take the steering apart and make sure it is cleaned and greased to avoid frozen steering next spring. Take batteries out and store down cellar, not on concrete floor, piece of wood. Also new Racor fuel filter each spring for Ethanol problems. I also drain fuel tank completely and use gas in snow blower or put in my car. Don't forget the trailer. Clean old grease out of bearings and repack in spring., especially if in salt water. One fried bearing on side of highway will teach you a lesson. That is my procedure, which I still have to do. Have fun. I won't.

Never use fogging oil on a 4 stroke = 1/2 a gal

Why Ronnie?

Not an outboard guy but I fog out my mercruiser at the same time I run antifreeze through it. I use either some fogging spray or slowly pour in some mystery oil.

Why Ronnie?

Not an outboard guy but I fog out my mercruiser at the same time I run antifreeze through it. I use either some fogging spray or slowly pour in some mystery oil.



They claim it could cause a hydrolock

Forgot to mention this motor is permanently attached to the boat as its a side console setup. I don't plan on removing it from the boat. Also, the garage its being stored in is heated. Does this change anything?

I wouldnt even winterize it. If its in a heated garage I wouldnt worry about it. Id just turn it over once every month.

who heats their garage?

who heats their garage?

Fruity golfers

I would definately winterize it. Change the oil and filter, drain and change lower unit oil. As for fogging, Yamaha reccomends it and in fact on my 150 there are special nipples so you don't even have to take off the spark plugs to spray the foggin oil in there, you just connect the fogging oil to the nipples to spray in. Then you crank the engine a few times without turning over. Good luck

Wonder where MTC has been, Tom from Cohasset?

He started his small engine/boat repair business and has done some tune-up work for some of the guys here. Thought he had posted an outboard winterizing thread a couple years back.

In a heated garage I would not be to concerned but I would run it in fresh water for a while until well warm, (to rinse out salt) then run a anti-freeze mix just to protect it. Change the oil/filters, at 20 hours you don't need to do the water pump impeller, but I would spray a light coating protective oil on the block just to keep it looking like new and inhibit any rust. Again, at 20 hours it is a new motor. Nothing wrong with some fuel stabilizer while it is being rinsed either.

Heated garage...nice!

Wonder where MTC has been, Tom from Cohasset?

He started his small engine/boat repair business and has done some tune-up work for some of the guys here. Thought he had posted an outboard winterizing thread a couple years back.

When I had my skiff Tom's shop handled all my issues. Tom will give you an S-B.com discount as well. He hooked me up with some cheap trailor parts too. My motor was a 15hp 4 stroke Yamaha which was very finicky. For the 3 seasons I owned it I would have to get the carbs cleaned twice a season which I thought was a PIA. I tried the addiitives during the season to prevent the gunk up but it was always the same story. I don't miss the maintainence but i do miss the skiff. I had some good little trips with her.

I have had a Honda 90 since 2000. I put stabilizer in the gas run for 15-20min on muffs, pull the fuel line and run it out of gas, drain the fuel bowls, change the lower unit oil and let it sit until spring. I change the crankcase oil and fuel filter each spring. Never had an issue until last year when I forgot to drain the fuel bowls, it idled like crap for about 20 hours of run time and then smoothed out back to normal. I decided this past spring to always put stabilizer in my fuel because of reduced usage.

Nice boat Mike,that has Gilligan's Island written all over it.

Just run the gas out of it.
So it don't turn to jelly over the winter.

That should do it.

I would definately winterize it. Change the oil and filter, drain and change lower unit oil. As for fogging, Yamaha reccomends it and in fact on my 150 there are special nipples so you don't even have to take off the spark plugs to spray the foggin oil in there, you just connect the fogging oil to the nipples to spray in. Then you crank the engine a few times without turning over. Good luck

I agree. Mike I have my Yami winterized by a Yami dealer and they fog the moter with something. I don't think its the same fogging oil they use on a 2 stroke but I know for a fact that Jeff fogs my motor. Started on the first crank last spring. They also do the same stuff that Prof M listed. I change my water pump impeller and thermostat every year. Probably could go 2 years but I run alot and don't want any issues in the Spring. The guys also run RV antifreeze thru all my water systems. Bilge pumps, raw water washdown and live well.