Proper antifreeze to winterize a boat engine

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I will bet 95% of the people use the cheap pink RV stuff from Walmart. Yet I believe it says not for engines. There is also pink stuff a little more expensive that is alcohol free but it also says not for engines.

West Marine sells antifreeze for engines that is a little more expensive than the cheap pink stuff. (still it's winterizing antifreeze, not coolant).

Fresh water system in boats and RV has copper, brass, bronze, rubber and plastic probably no iron or aluminum like an engine would have. So maybe it's the low level of corrosion inhibitors for steel and aluminum?
 
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RV antifreeze that contains a mixture of propylene glycol and alcohol are not recommended for winterizing engines. Regular RV antifreeze containing no alcohol is recommended for winterizing marine engines. The West Marine stuff you mention is regular RV antifreeze. They recommend it for winterizing fresh water systems as well as engine cooling/exhaust. Whether you buy the Walmart brand RV antifreeze or the more expensive West Marine brand is up to you.
 
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Pink RV winterizing fluid is not for recirculating use in an engine, since it has no anticorrosion additive package. It is fine to leave in the seawater side during storage. A system built for untreated water doesn't need corrosion inhibitors.

The published MSDS for SuperTech RV antifreeze does not list any antifreeze other than PG, (thus it is an alcohol free formulation) but it would be good to check the label of the particular bottle you're buying.
 
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You could use standard AF to winterize an engine, but it’s going straight into the water as soon as the boat is started. Propylene glycol AF (like RV AF) would be a little better for the environment-why not Sierra coolant or similar?
 
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Looks like Academy also sells the same stuff for $6.99 a gallon, safe for engines. (Starbright)

There is something a little funky about the marketing of these products, they state -50F but you have to read the wording on the product because it starts jelling at around 18F The -50F is the temperature that a copper pipe would burst which is weird.

This is also right from the West Marine site. They sell both products, Start Bright and West Maine for $9.99
This is the wording from the West Marine product and StarBright =

"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"

(https://www.westmarine.com/antifreeze/)

I think you are going to need the -60F that will protect down to 10F $13.00 a gallon
or the -100F that will protect down to -58F $21.00 a gallon

I actually didnt even know these products existed. I always thought they were all no good for engines. Regular antifreeze always seemed the safest. Not sure I would trust any of them except the -100F

Actually they give you the temperature points of when not to trust them, in the small writing that many do not read. Obviously its marketing using numbers that the public equates with regular automotive antifreeze, very dishonest.
 
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Donald

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Looks like Academy also sells the same stuff for $6.99 a gallon, safe for engines. (Starbright)

There is something a little funky about the marketing of these products, they state -50F but you have to read the wording on the product because it starts jelling at around 18F The -50F is the temperature that a copper pipe would burst which is weird.

This is also right from the West Marine site. They sell both products, Start Bright and West Maine for $9.99
This is the wording from the West Marine product and StarBright =

"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"

(https://www.westmarine.com/antifreeze/)

I think you are going to need the -60F that will protect down to 10F $13.00 a gallon
or the -100F that will protect down to -58F $21.00 a gallon

I actually didnt even know these products existed. I always thought they were all no good for engines. Regular antifreeze always seemed the safest. Not sure I would trust any of them except the -100F

Actually they give you the temperature points of when not to trust them, in the small writing that many do not read. Obviously its marketing using numbers that the public equates with regular automotive antifreeze, very dishonest.
The really issue is when do they expand. But I agree the temps listed are hard to decipher.

In a car if the coolant gelled in the winter and would not circulate that would not be good. But in a boat engine that was winterized, you don't care if it gells as long as it does not expand.
 
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I have used the WM -100, it’s good but expensive. I switch to the Sierra PG engine coolant mixed 50/50 that gives freeze protection down to -26*F. Cheaper than -100 ($14/gallon after mixing) but more than -60.
 
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The cheapest solution is to use some Super Tech automotive coolant.
Call me crazy but I think the part that I loved about the closed cooling system was every winter I would make sure the engine was well flushed out with fresh water and then there was a drain or two at the bottom of the heat exchanger I let the water run out and that was the end of it.
I don’t think I put any kind of coolant in there but it was a couple decades ago🙃
 
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I have used the WM -100, it’s good but expensive. I switch to the Sierra PG engine coolant mixed 50/50 that gives freeze protection down to -26*F. Cheaper than -100 ($14/gallon after mixing) but more than -60.
AFAIK the propylene glycol Sierra coolant is a similar chemistry to the pink RV antifreeze-but Sierra will have inhibitors to prevent corrosion of steel & cast iron parts. Not too sure RV antifreeze has those, since it's basically supposed to be almost drinkable, since it's used in a potable water system, that is usually plastic, brass, possibly copper.
 
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The cheapest solution is to use some Super Tech automotive coolant.
But when you fire up the engine in the spring you're putting toxic ethylene glycol antifreeze onto the driveway or even worse into the water....
The only stuff I use is Sierra PG mixed with water to -30*F freeze protection, or the West Marine -100. The -100 is more convenient but costs about $7 more a gallon. I use about 4 gallons each time I winterize the boat (engine + exhaust system). So far it's been in salt water 20 years and the intake manifold/block have not rusted out.
 
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And what comes out of every vehicle in an accident? And where does it go? Including EV coolants.
Sea Doo is lucky to hold a pint in the winterization mode.
 
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I think there's a difference between an accident where oil, AF or fuel can be spilled vs starting your boat up in the water at the ramp every spring putting ethylene glycol right into the water....Accident vs willful....there is a difference.
 
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