Outboard Winterization

I know it is still early, but I have a new (used) boat with a much bigger outboard than I am used to, Mercury 115 EFI 4-stroke. My smaller outboards, mainly my Yamaha 25hp 4-stroke, I have always pumped RV/marine anti-freeze though it to winterize. I made a custom earmuff setup so I can attach the anti-freeze bottle directly to it, and I run the motor on sucking the anti-freeze though it. I also have done this on I/O’s on my wifes ski boats for many years. Never once had any issues.

Anyways, I have been watching videos on winterizing Mercury EFI 4-strokes and it never states anything about flushing them with anything. I was told once that the newer designs, with the motor in a vertical position, will drain out all the water, with no worries of freezing. I always change engine and lower unit lube, making sure not water exists there.

So just wondering, for you DIYers, do you trust that the motor drains completely and not worry about freezing?

As many other late season fisherman do drop the motor and let it self drain. Motors have never been a problem for me, but interior plumbing and pumps have. Want to check wash down pumps and make sure those are clear of water. If you use rv antifreeze make sure to flush the lines at home before you go back on the lake.

Newer meaning for the last 40 years. Just put the outboard verticle and the water will drain, tilt it back up before driving down the road.

be leery of rv antifreeze , I had a jug of minus 50 deg a/f freeze solid and expand the jug so it wouldn’t stand up at zero degrees

cheers wrote:

be leery of rv antifreeze , I had a jug of minus 50 deg a/f freeze solid and expand the jug so it wouldn’t stand up at zero degrees

Way back in the day of pumping gas for people I had a kid working for me who sold the same gallon of windshield wash 25 times. He just kept adding water and blue food coloring. Took me several weeks to get onto him. He was doing the same with oil. He would short stick you when checking your oil. “Add” the already empty quart and show you a dip stick that said you were good. The kid was good.

I run my fishing boat all winter and my duck boat until freeze up, I always just drain the motor and its good, we fish the river most of the winter when its well below freezing. I have never had a issue

this anti freeze came from the save big money store

Just drain it vertical and it will be fine.

I guess I am just overly cautious. I guess I figured there was more to it because dealerships charge $150-$200 for winterization. I think I will still run the RV/Marine antifreeze through it, its cheap and easy, but let it drain out before putting it away.

The comment on making sure to drain the antifreeze before it goes in the lake, my understanding, and it is printed on the bottle, is that this antifreeze is non-toxic and environmentally safe. So although still a good idea, not sure it is a requirement.

Good suggestion on the other plumbing though, live wells and pumps, that is new to me, will have to remember to flush them down as well.

The comment on making sure to drain the antifreeze before it goes in the lake, my understanding, and it is printed on the bottle, is that this antifreeze is non-toxic and environmentally safe. So although still a good idea, not sure it is a requirement.

Products that say environmentally safe and non toxic does not mean they are safe to be put into lakes. You can do your own research but after you will agree. I like fishing to much to harm it. Good luck

On my 115 oil change w/filter, lower gear oil. Spark plugs every 4 years, water propeller every 6. No issues for the last 20 years.

Drain the motor by leaving it vertical overnight. I have also seen marine antifreeze freeze solid. No need.

Pull the plugs, spray a little fogging oil in the cylinders, replace with new high-quality plugs that’ll cost you $10-20/year. Once the plugs are back in, turn the motor over for a second to distribute the fogger. Plugs are cheap. Change them every year. Then you know they’re good and properly gapped. If I try to get 2-3 years out of mine, they need re-gapping. Over the years, before I started changing plugs every season, there were numerous times the motor started running a little rough, and new plugs were the fix.

Couple pumps of grease into the tilt/trim. Might as well do a couple pumps into the trailer bearings and trailer jack as long as you have the grease gun out.

Remove the prop, look for fishing line, observe the seal for cracking. Hit the splines with a little grease from the gun. Replace the prop.

Drain the lower unit overnight and replace with the good stuff. Observe for water pouring out of the bottom hole when the plug is released. It’ll look like a drinking fountain for a second or two if you have major seal leakage. If the oil went in clear and comes out milky, that means there’s a trace of water in it. You could literally spit in the fresh oil, run around the lake a few times, and it’ll be milky. That’s fine. Continue to observe and maybe start changing the lower unit 2x per year. The drinking fountain however, not fine. That needs professional repair. I’ve had milky oil for the last 6 or 7 years and the boat runs great and gets used a ton.

Leave as little gas as possible in the tank, and treat with Marine Stabil and Seafoam. Always use non oxygenated 91 premium.

Next season, fill up the gas tank to dilute the old gas, and the motor should perform as well as it did on the last trip of the season.

Before using any fogging oil check what the manufacturer recommends, as Mercury does not recommend fogging the 2 stroke Optimax engines as the fogging oil can block the oil and gas injectors. Me four stroke motors run some Seafoam or stabilizer at the end of the year check lower unit good to go.