RV antifreeze for boat storage

[LeonL]

Any of you guys use the pink RV antifreeze for winter storage? What is the low temp protection?

[IGski]

The stuff I use said -50 F. I always pull all my plugs and drain after I suck it in. Just an extra precaution. Some guys leave it in the motor but not me... And don't forget the heater hose if you have one.

[oldjeep]

I use the -100 stuff. First drain the whole engine and heater core, then pour in the antifreeze

Whatever you use, get the stuff that is meant for engines, not toilets. I leave it in for the corrosion protection.

[BraceMaker]

@LeonL - depends on your goal and frankly how cold it gets where you are.

 

Remember Wind Chill has no effect ie. 10 with a -50 wind chill is just 10 degrees (But it gets to 10 degrees a lot quicker) i suck pink in with the block drains still open. Usually 2-3 gallons or so and it starts to spray out the exhaust and then when you shut it off the pink juice drains back out of the block and head.

 

I don't then remove hoses to try to get all the pink out which means that on start up there is still stuff around.

[Deanoski]

pull the boat out of the water when hot use a 5 gallon bucket fill it up with -50 pink and hook it to the intake hose

 

l start the boat turn on heater core and hot water shower so they get filled with -50

 

I use 6 gallon its over kill but never had an issue in 30 years of doing this

 

I live in eastern WA so it is cold in the winter.

[BraceMaker]

That method works if the thermostat is actively open - the failure point is that if you didn't get the engine good and hot or if you took too long pulling it out the thermostat can close and trap water in the heads.

[jepski]

To @BraceMaker 's point, I'm always concerned the t-stat might close or be closed using the bucket method. So, I just drain the block, manifolds, remove lower water hoses and drain them. Then reconnect them and remove top water pump hose and fill with AF and reconnect. Remove manifold hoses and fill with AF (or until AF drips from exhaust), then reconnect. I leave the AF in for the winter.

[PurdueSkier]

I do as @jepski listed above. If you dump it in the hoses you dont have to worry about the tstat being closed. I always drain the water first.

[A_B]

I do exactly as @Deanoski does. Northern Ohio. @oldjeep is in the arctic tundra so needs -100.

[oldjeep]

The only reason I use the -100 is it is only $3 a gallon more than the -50, so for $6 a year - why not. That way if I really screw up and there is still water in the block it should get diluted and still have enough freeze protection.

 

Boat lives in my garage and realistically never gets below 0F because of all the heat soak from the house.

[LOTW]

Over the last few years, I have noticed that there has been an accumulation of rust and other crap that plugs up the drain holes. Be sure to take a nail or piece of coat hanger and poke that stuff out so all of the water drains and doesn't get trapped in the block or manifolds. This applies to all outboards not just ski boats.

[Sethro]

One year I forgot to put the block plugs back in before pouring antifreeze through the manifolds. I usually just take one hose off as the perfect pass servo is on the other. When filling the starboard side manifold from the port side hose, it is "above" the thermostat, antifreeze came rushing out the block plugs. So every time I hear make sure the thermostat is open I wonder if it's really necessary.

 

I think it's good advice, and I'm sure much more flows through the system when it's open vs. what will flow through the tiny air bleed hole.

[keithh2oskier]

Is there any benefit to using RV antifreeze if you dont need freeze protection? I am in Nor Cal where I don't have to worry about freezing temps. My winterization process is fuel stabilizer and a battery tender but I dont bother to drain the block. I am wondering if there is any benefit to using RV antifreeze to prevent build up from the raw water that sits in my block for 6 months? For what its worth, this has basically been the procedure my dad has used on his ski boats since 94 and we have never had a mechanical issue.

[mmskiboat]

If you want some real life tests this is a very good read:

 

https://teamtalk.mastercraft.com/showthread.php?t=70342

 

If you want to jump to some results go here:

https://teamtalk.mastercraft.com/showpost.php?p=1253235&postcount=43

 

Short answer is storing the block full of propylene glycol is a solid choice.

[6_Buoys]

I pull all the drain plugs and hoses, including to/from heater core, and drain all water out. Leave drain plugs out and begin to refill with pink anti freeze. When pink drains from plugs, then replace the drain plugs. I like to have liquid in the engine when I start it up next spring.

[BraceMaker]

@Sethro while it's true it will do that if all of the block is full of water it has to displace that water.

 

The job of the thermostat is to regulate the mixture of new cold water with the old hot water. The unnecessary cold water goes out the back. Even if it's your fresh antifreeze

[terryg]

Most RV/Plumbing antifreeze is meant to be used in plastic pipes and does not have the anti-corrosive properties of traditional automotive coolant. Make sure you if you use the pink stuff, that it clearly indicates it is safe in metal.

Leaving the block empty will allow rust to form, so even if the temps don't drop too low, its best to fill block with antifreeze vs drained.

[LeonL]

I've always used automotive AF with no problems. Can't address internal rust. I don't know if what I used is propylene or not. Just curious about RV. I think I'll stick with auto AF but insure that it's propylene.

[Killer]

You shouldn't use automotive AF, unless it's a closed cooling motor. I'd think in most jurisdiction spilling it on the ground would be considered illegal dumping. It's toxic. RV antifreeze is not toxic.

 

My motor is 18yo. Zero issues.

 

We had a '79 351 that was running strong at 30 yo. We just drained that one, no antifreeze. Lost 1 Frost plug in 15 years.

 

There is no need to use or keep antifreeze inside the motor over winter. Drain water, backfill with RV antifreeze and drain to flush. Our air temps get to -30F in the winter. Many don't even use RV antifreeze and just drain.

 

 

[keithh2oskier]

@Killer without worrying about freeze protection in my case, is there any issue with just leaving my block with lake water all winter? I kinda assume not since realistically my engine sits with lake water the 6 months I use it during the summer. Its not like the lake water changes properties or would likely become more corrosive by sitting there in a garage during winter months than sitting there in the garage during summer months...

 

I am probably overthinking this and should just keep it business as usual.

[PatM]

I drain everything like all have mentioned here and run RV antifreeze through after putting back plugs. I was wondering what everyone's thoughts are on fogging the motor in the process? I used to do it pre - Cats, but now am told not to fog because it screws with the cat converter.

[UWSkier]

Northern WI the boat is often in -20F temps in winter. For 18 years, been draining down the block and manifolds and cranking engine over a few times with lanyard pulled. Blow pink through heater core but block sits empty. Chemical reactions slow down a lot in the cold. You're just as likely to have rust form in the summer when the inside of the block is warm and steamy (and full of water). I don't buy the corrosion protection argument but to each their own.

 

Fogging pre cat engines is a good idea for actual corrosion protection where it matters most. :)

[mmskiboat]

@UWSkier In the other thread the propylene glycol did provide corrosion protection over a dry block. But your point is well taken that it is happening during the summer so you are only slowing it down not preventing it from happening at all. Also this was just a test with metal in plastic containers (over 7 months).

[Killer]

@keithh2oskier I don't see why not if there is zero risk of a snap freeze. Why not take er out for a mid winter rip!

[6balls]

We are in MN...it gets cold. Never a problem with motor warm at full ops temp so t-stat is open sucking 4 gallons of anti-freeze into the motor. Run a garden hose into the block, let it idle to ops temp, have your bucket of anti-freeze ready. Once at temp, disconnect garden hose and use a short hose section to the bucket of anti-freeze and slurp it up.

 

Make sure no air leaks at the connection of hose to motor...I had an air leak this year and initially it wouldn't slurp up the anti-freeze well til that problem solved.

 

Question: when turning on my heater does that open a valve and run hot water thru heater core or is it simply turning on/off a fan. I'm thinking a fan only and that the water runs thru the core...but I may be full of it. The reason I think so is one year we got in the water early in the spring, then had a freeze. Motor did fine but heater core cracked and every hole shot it was hot water on the feet. Makes me think the water goes thru there regardless.

[BraceMaker]

The heaters generally circulate fluid based on a Venturi effect where a y fitting in the intake flow draws hot water off the block through a heater core and back into the intake stream.

 

The heater switch is just a fan that blows air through the core.

[BraceMaker]

A cool season experiment would be to take a cold boat that's not winterized, prep a bucket rig and pull 1 gallon of antifreeze in then drain a sample out of the block.

 

Repeat pulling more and more antifreeze up to say 6 gallons cold.

 

Then repeat on a hot engine.

 

The samples would be frozen using dry ice and then thawed taking the temp of the solution when it thawed.

 

[mfjaegersr]

I'm curious, @Deanoski: what do you mean by 'turn on heater core'? I take it to mean you have a shutoff valve to block flow to/from said core?

[BobF]

I use the -60 that has some advertised corrosion protection. I like that the diluted freeze protection is still sufficient, just in case.

 

Slightly ot, regarding the heater: I put a "Y" hose valve at each end of the heater with a short amount of unterminated hose on one side. This allows the heater core to be blown out if it's going to go below freezing, and also allows AF to be poured directly through the core for winterizing. Bonus that it allows the heater to be shut off in the summer, when you can use it as a fan in between sets. :smile:

[Deanoski]

@mfjaegersr heater core is the drivers hot air heater that runs off the hot water in the block

[mfjaegersr]

@Deanoski I know all about the heater core. Your statement of ‘turn on heater core’ is vague; could be read to mean you think that turning on the heater (fan) switch will start the flow of AF to the core. (Which is not the case, and might mislead others.)

 

I was hoping maybe you had plumbed the core in a way that allowed you to turn flow to it on/off from the block, perhaps even divert and drain easily without disconnecting the hoses.

[oldjeep]

There is a pump kit that some folks add to their heaters. https://www.wakemakers.com/heater-craft-circulation-pump-retrofit-kit.html

 

[BraceMaker]

@mfjaegersr you can perform this with a simple ball valve at the heater line to restrict the flow. In this way it is just a block drain.

 

However with the fluid circulating typically the users don't "feel" much heat coming out of those long vent tubes since there is no active push of air through the heater core.

 

Ideally when not in use the heater would be drained and essentially winterized as lake water sitting in them all summer causes them to rot out every few years for most.

[BrennanKMN]

I always disconnect my heater core hoses after draining the engine water and just blow the water out with my mouth. Then use a funnel to feed in about 1/2 gallon of antifreeze blowing it through between each 1/2 quart or so until you can see it run out into the bilge through the other hose. Then I replace the hoses and run the engine on antifreeze to refill the engine.

 

Pretty simple and works for me.

[mfjaegersr]

(Hey - who’s the elephant over there?)

 

So - what is the de-winterize process for those of you that use the fill with AF method? As in, how are you responsibly dealing with the AF that’s coming out when you start up in the spring? Particularly folks using the toxic stuff. ?

[BobF]

@mfjaegersr If non-toxic RV a/f is used, it's not an issue. I start on a hose, in the street, in front of my house, to make sure it starts before I hit the water. Just let it fly.

[MISkier]

There are non-toxic solutions other than automotive AF that protect just as effectively.

 

My dealer used this in my MasterCraft 205 years ago:

 

https://www.westmarine.com/buy/star-brite--pure-oceans-200-f-super-concentrated-antifreeze-gal--14823355

 

For my Malibu over the last 10 years, the dealer uses the pink RV antifreeze.

 

Both are de-winterized by just starting in the driveway. The blue AF would kill the grass, though. The pink RV AF has no negative affect on the grass.

 

[BraceMaker]

@mfjaegersr while you obviously don't want to dump 100s of gallons of antifreeze into the lake RV antifreeze is typically flushed into the septic systems at campgrounds and is sewer safe

[EFW]

You guys over complicate everything. I've used high quality windshield washer fluid for over 30 years. No problems ever. Put a small container with the same solution next to it to keep an eye on it when it gets cold. Down to 16 below I've had no problems. We're not talkin the North Pole here . You get a nice day in January do you want to take the boat out start it up and go. You don't have to feel like you just dumped 50 bucks down the drain.

[BrennanKMN]

I paid less than $20 bucks for 6 gallons of -50*f RV & marine antifreeze. Pretty cheap if you ask me...

[2Valve]

Been using it since I got my Inboard back in '03. Never a problem.

 

Mine takes about 2-3 gallons

[Booze]

Now I'm confused, because the RV stuff may be propylene glycol, which is supposed to be better for anti-corrosion. I'll have to read the labels to confirm.

 

[MISkier]

@Booze, your heater core may be getting sediment from the lake, especially when idling in shallow water. That can harden like concrete and obstruct the core. Then, it can also trap some water when, as you noted, it becomes more resistant to blowing out. The trapped water can freeze and cause the core to break.

[A_B]

The rust articles were good to see, but rust is not as hyper active when we store our boats during the winter, and actually is very rapid to form in hot weather. A better test would have been to take the metal samples and placed them in a freezer.

 

I used good old 50/50 Prestone for years and fired the boat up in the yard and killed the grass every year and got tired of having dead spots in the yard and getting ragged on by the boss, so I went to the RV Pink -50 stuff a few years ago. I always believe the green AF was helping lubricate the impeller for storage and restart in Spring. I am not a believer in the drain all fluid method without any AF being introduced.

[mmskiboat]

A better test would have been to take the metal samples and placed them in a freezer.

@A_B Had not thought about that and would make it even more realistic. Perhaps there was an issue with the boss about having tons of rust samples in the freezer for 7 months :-)

[Jordan]

FWIW, the Indmar manual for my LT1 calls for dry blocking. They used to be concerned about antifreeze reacting with the aluminum heads. My understanding is that the RV antifreeze is fine; however, I have been following the originally suggested procedure for 15 years.

 

I pull the two plugs and the Knock sensor. I also pull the exhaust manifold plugs. Then I disconnect the oil cooler and make sure it is drained, last thing is disconnecting the raw water pump hoses and I pull the impeller.

 

Additional notes: I add Stabil to the fuel tank earlier in the fall. Battery comes out and gets charged up and spends the winter at home. I also change the oil and filter before storage.

 

This procedure has worked without issue for 15 years in very cold Canadian winters. After 1650 hours the engine is as strong as ever.

 

[A_B]

I just found a blue marine Stabil that I dumped in the tank before the last run. I didn’t know they made a specific marine product. Not sure what the difference is.

[S1Pitts]

I have been using the marine version for years. Engine always starts in the spring like it has been running all day but I noticed it does not smell near as bad as other brands when you are burning out that first tank in the new season.

[fu_man]

@A_B I looked at Stabil's website regarding the differences between blue marine and red regular and I am still unclear.

[oldjeep]

@fu_man marine unicorn tears vs regular unicorn tears. Last time I looked at the msds on them, one was mostly propanol and the other was mostly naphtha