PSA on Winterization Antifreeze

tpenfield

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It is that 'special' time of year in the northern regions where boats (and their engines) need to get winterized. Based on the winter incidents from last year (or 2), we are now including Texas as a 'Northern' state in the USA :ROFLMAO:

Anyway, as a Public Service Announcement . . . Please be aware that the Antifreeze ratings that you see advertised, like -50˚F, -100˚F, etc. are PIPE BURST ratings, which is a rating established by the plumbing industry in the 1930's (or so). It is the temperature at which a copper pipe will burst. The actual freezing and expansion of the AF starts at much higher temperatures and can (does) damage plastic parts in a boat engine's cooling and/or a boat's plumbing systems.

Knowing this fact, companies (like West Marine) have provided guidance on the spec's for the Marine AF that they sell. Here is the info from the -50˚F AF . . .

"Ideal for regions that experience temperature ranges between 14°F to 18°F (-8°C to -10°C); for colder regions we recommend using non-toxic West Marine antifreeze with a -60°F or -100°F rating"

Folks in many northern regions may want to be thinking about the lower temperature rated AF versions (-60, -75, -100) to provide adequate protection.

FWIW - I was fighting a fresh water system leak in my boat all summer only to find out that the plastic strainer bowl that is between the water tank and the pressure pump had cracked due to prior insufficient winterization (i.e. -50˚F). Years ago my sea water strainer (on a previous boat) suffered similar fate (cracking) from using the -50˚F stuff where winter temperatures reached around -10˚F.

My 'new' boat has sea water strainers and a few other plastic parts in the engine cooling system that could experience similar fate at temperatures approaching 0˚F and lower.

Then there is the whole PG vs. Alcohol thing, but that is a story for another time 🤪
 

Lou C

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if you get temps down to zero and want to use -50 or -60 try putting it in the freezer at zero & see what happens…it gets hard…to me that means it doesn’t belong in a cast iron engine that will see temps that low. I mix up my own Sierra PG antifreeze with water. Mixed 50/50 it gives freeze protection of -26*F at a cost of about $15 a gallon. I used to use the WM -100 that stays liquid down to -50* (overkill for my location) @ $21 a gallon. Either way you’re protected much better than with the -50 or -60.
 

briangcc

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The marina that winterizes mine, which happens to be an authorized Merc and Volvo dealer/repair center, leaves the system empty. We freeze, hard sometimes, in NY.

Take it for what its worth.
 

WIMUSKY

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I've had jugs of RV antifreeze freeze solid too sitting outside. I use a low point drain and then blow out the lines. Air doesn't freeze.... That being said, I have drained an engine block and filled with rv antifreeze w/o any issues....
 

matt167

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I used 2 gallons of -50 supertec rv antifreeze to winterize my 3.0l. But I drained and filled the block and manifold and then drained it out fully. Any remaining will not freeze in a NY winter since air doesn’t freeze. Doing so reminded me how much I really don’t like an I/o. probably going to take my little boat out in a week. I’ll run some stabil through it.
 

Lou C

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FWIW, I'd either use my mix of Sierra/water, or -100, or just leave it dry I don't trust the other stuff even though it is widely used. In my climate a -75 might be fine if I didn't want to mix but its harder to find.
However, I feel that the corrosion inhibitors in the better AF do reduce corrosion in storage, in fact Merc specifically recommends using AF for that reason.
Pick up one of these refractometers if you mix your own, more accurate than the old style plus it works on PG antifreezes.
antifreeze & refractometer.jpg
 

airshot

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I have always drained my system as well as I could, then pour a couple gallons thru the system just in case any water was trapped in there. For the less than 5 bucks it cost for two gallons of antifreeze, it was a great piece of mind. RV antifreeze is actually good for seals and plastic parts
 

tpenfield

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It seems like much of the affordable antifreeze is alcohol-based, but supposedly is not good for the engines 🤔
 

Scott Danforth

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It seems like much of the affordable antifreeze is alcohol-based, but supposedly is not good for the engines 🤔
That's odd, because before AF, cars were drained and the cooling system were filled with alcohol
 

tpenfield

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That's odd, because before AF, cars were drained and the cooling system were filled with alcohol
Yes, I think it has to do with rubber gaskets and plastic parts being dried out by the alcohol (so, I've read on various sources). I've noticed that many of the lower priced AF also say not intended for engine winterization.

Might be a marketing plot though . . . since the PG type is about 3X the cost. o_O
 

matt167

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Someone told me that pink rv antifreeze is PG and red is alcohol based. But I’ve never paid attention if that is true. Fwiw a lot of the rain x windshield washer fluid marked -35 is pg if you read the contents. I think it’s why it smears the glass.
 

tpenfield

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I was going by the colors as well, but after reading the fine print and checking the MSDS sheet, I realized that you cannot depend on the color. I have jugs of both pink and red that are alcohol-based.
 

Lou C

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Watch out for the windshield washer stuff the alcohol in it is methanol which is poisonous; not ethanol which of course is not…
 

tpenfield

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@Lou C - Regarding the Peak/Sierra AF . . . it is interesting that it is marketed as a coolant rather than a winterization product. The data sheet indicated 95% PG, so it is concentrated. Not sure what the dilution ratio would be to get the desired strength, but the melting (freeze) point is -76˚F.

I might have missed it, but do you dilute it? and if so by how much?
 

Lou C

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I mix 50/50 & that gives you a freeze protection of -26*F. Yes it is really an engine coolant the main difference between it (PG) and other engine coolants (EG) is mixed at the same %age it doesn’t provide as much freeze or boil over protection but for this purpose it’s fine. You could always mix at 60% in a real cold climate. I know the WM -100 is $21 a gallon and my mixed Sierra is $15 a gallon.
PS
You need an antifreeze refractometer to measure the strength of PG antifreezes…
 
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tpenfield

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You know what is interesting . . . Propylene Glycol has a freeze point of -74˚F . . . so the "-100F" antifreeze must be frozen long before it gets to -100 degrees.

I think the guidance is to use it in temperatures down to about -60˚F . . . probably all anyone would ever need. (except Antarctica in July :ROFLMAO: )
 

WIMUSKY

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Doing so reminded me how much I really don’t like an I/o.

One of the reasons I went back to an outboard. Soooo much easier to maintain on all levels. Gotta love self-draining. And of course, access to the motor. Contorted body not needed... At least the I/O I had...
 

tpenfield

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One of the reasons I went back to an outboard. Soooo much easier to maintain on all levels. Gotta love self-draining. And of course, access to the motor. Contorted body not needed... At least the I/O I had...
Yup, I said that to myself a while ago with my previous boat. . . .

Then I went boat shopping . . . o_O $$$$$$$$$$
 

Jmunk

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I mix 50/50 & that gives you a freeze protection of -26*F. Yes it is really an engine coolant the main difference between it (PG) and other engine coolants (EG) is mixed at the same %age it doesn’t provide as much freeze or boil over protection but for this purpose it’s fine. You could always mix at 60% in a real cold climate. I know the WM -100 is $21 a gallon and my mixed Sierra is $15 a gallon.
PS
You need an antifreeze refractometer to measure the strength of PG antifreezes…
Are you buying the Sierra locally?
 
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