[Minnewaska]

The RV/marine potable water anti-freeze products can typically be used on the raw water side of an engines cooling system. The tread seems to be confused with the coolant inside the captive side of what's called a fresh water cooled system. It's poorly names. I substantially prefer to use -100degF on the raw water side, which the sales guy at WM always thinks is crazy in RI. However, these ratings are for bursting, not freezing. They freeze at much warmer temps. Further, any dilution seriously degrades their capability. The -100 product can be diluted almost 50/50 and still be perfectly effective in our winters. I worry about dilution in the raw water system and holding tank, in particular.

The ubiquitous pink stuff is rated at -50degF. This will typically freeze at a positive 8F to10F, if undiluted.

As for the fresh water system, nothing gets added there. Ever. I said, ever. I blow the entire system out with a compressor.

 

[chef2sail]

I highly recommend Zerex G-05 (aka mercedes benz) coolant. It has much better corrosion inhibitors than anything else, and will make your coolant system parts last much longer. I like to mix it 50/50 with distilled water, since most tapwater is somewhat corrosive also.

Different engines have suggested antifreeze. My Yanmar is a Texaco product.

 

[MikeOReilly]

I've always run engine coolant through the raw water side of my engine's cooling system as part of my winterizing. In part, I do this b/c this was the way I was originally taught. I also wonder if the anti-corrosive additives makes it a better choice, but I admit I don't really know.

I have wondered about using the non-toxic stuff, which I already use everywhere else. I have no concern about the -50C rating. Even when I sailed out of northern Ontario, where we would get real winters, -50C would have been fine. There is nowhere that people sail (that I'm aware of) where -50C would not be fine.

 

[pdqaltair]

No, RV antifreeze does not meet, really, ANY of the requirements for engine coolant (20 years in the industry, including active participation in ASTM, developing tests). No, it does not have the same anti-corrosion properties. Testing has been published in Practical Sailor.

The sole advantage of RV AF is that it is non-toxic to mammals. That is important in the potable water system, but nowhere else. Both are biodegradable, recyclable, and non-toxic to marine life.

 

[WhatTheKell]

No, RV antifreeze does not meet, really, ANY of the requirements for engine coolant (20 years in the industry, including active participation in ASTM, developing tests). No, it does not have the same anti-corrosion properties. Testing has been published in Practical Sailor.

The sole advantage of RV AF is that it is non-toxic to mammals. That is important in the potable water system, but nowhere else. Both are biodegradable, recyclable, and non-toxic to marine life.

So if I use engine coolant rather than RV AF to winterize my raw water cooled Yanmar I won't be killing fish when I splash the boat in the Spring?

All things being equal, I would prefer the anti-corrosion properties you get with regular old Prestone type AF.

 

[MikeOReilly]

No, RV antifreeze does not meet, really, ANY of the requirements for engine coolant (20 years in the industry, including active participation in ASTM, developing tests). No, it does not have the same anti-corrosion properties. Testing has been published in Practical Sailor.

The sole advantage of RV AF is that it is non-toxic to mammals. That is important in the potable water system, but nowhere else. Both are biodegradable, recyclable, and non-toxic to marine life.

As I suspected. But how much do these anti-corrosive properties matter when we're talking about winterizing? We're not talking about using it in the closed system. Just running it through the open (raw) system to flush out water and ensure things don't freeze and burst.

Do the properties necessary for engine coolant really matter for this application? Or perhaps I should say, how much does it matter. I really don't know. Has that been tested PDQ?

I've always used standard engine coolant for the task. I do my best to collect the used anti-freeze before launch, but inevitably much gets spilled into the water. I always feel a tinge of gilt over this, and would feel less guilt if it were the non-toxic stuff. But I certainly don't want to risk damaging my engine.

 

[pdqaltair]

As I suspected. But how much do these anti-corrosive properties matter when we're talking about winterizing? We're not talking about using it in the closed system. Just running it through the open (raw) system to flush out water and ensure things don't freeze and burst.

Do the properties necessary for engine coolant really matter for this application? Or perhaps I should say, how much does it matter. I really don't know. Has that been tested PDQ?

I've always used standard engine coolant for the task. I do my best to collect the used anti-freeze before launch, but inevitably much gets spilled into the water. I always feel a tinge of gilt over this, and would feel less guilt if it were the non-toxic stuff. But I certainly don't want to risk damaging my engine.

No, it's probably not very important for seasonal storage. The article included corrosion testing of RV AF. The better brands did OK.

There is NO DIFFERENCE in marine toxicity between EG and PG. Look up the MSDSs and see. Not birds. Not reptiles. Not fish. US Fish and Wildlife have stated this. Only mammals.

 

[MikeOReilly]

No, it's probably not very important for seasonal storage. The article included corrosion testing of RV AF. The better brands did OK.

There is NO DIFFERENCE in marine toxicity between EG and PG. Look up the MSDSs and see. Not birds. Not reptiles. Not fish. US Fish and Wildlife have stated this. Only mammals.

Thanks PDQ, very helpful. So given this, it would seem that it really doesn't matter which antifreeze we use - at least from an environmental impact.

But interesting the differing toxicity impacts on differing animal classes. Seems rather odd that the non-toxicity applies only to mammals. Do you think/know whether this is a case of simply not being tested sufficiently on these other classes to know either way?

 

[pdqaltair]

Thanks PDQ, very helpful. So given this, it would seem that it really doesn't matter which antifreeze we use - at least from an environmental impact.

But interesting the differing toxicity impacts on differing animal classes. Seems rather odd that the non-toxicity applies only to mammals. Do you think/know whether this is a case of simply not being tested sufficiently on these other classes to know either way?

This has been tested a lot. Many studies related to deicer runoff at airports. Many of these use many hundreds of thousands of gallons each year.

 

[MikeOReilly]

This has been tested a lot. Many studies related to deicer runoff at airports. Many of these use many hundreds of thousands of gallons each year.

Thanks. I appreciate the clear answer.

So my take away is that I might as well stick with the engine (toxic) coolant. It has the slight advantage of various anti-corrosion additives. And neither are good to the marine environment.

 

[MastUndSchotbruch]

Thanks. I appreciate the clear answer.

So my take away is that I might as well stick with the engine (toxic) coolant. It has the slight advantage of various anti-corrosion additives. And neither are good to the marine environment.

Sounds right.

There is one other difference: the RV version costs about $3.- a gallon, the car coolant version about $10.- (or more, depending on brand and where you buy it).

 

[TakeFive]

1: I've successfully used Marine RV potable water or Fresh water winterizing antifreeze to winterize the raw water side of my Marine Engine. Marine West has two different products for this one cost 50% more then the other both essentially do the same thing so whats the difference?

West Marine has doctored the photos on their website to make them both look "pink." The cheaper stuff is actually orange, and by industry convention that color indicates that the antifreeze contains a mixture of ethanol and propylene glycol. The more expensive stuff has no ethanol, and the only active ingredient is PG.

For use in raw water equipment and heads, the ethanol may leach plasticizers out of seals, raw water impellers, etc., making them brittle and prone to leakage. (Same problem caused by 10-15% ethanol in gasoline fuel systems.) I pay the extra to get the pink stuff (and sometimes purple if I want extra protection).

For those who use the pink or orange stuff in potable water systems, I believe that the orange stuff has bitter tasting denaturants (required for any manufacturer who wants to avoid liquor taxation of their ethanol). The PO of my boat used the orange stuff in the potable water tanks, and it has taken three years for the bitter taste to work its way out.

 

[TakeFive]

I went to Walmart today to buy Rotella for my diesel. While waiting to pay I saw a stack of pink stuff for $2.57. Surprised that they had the “good” propylene glycol stuff, I picked it up and checked the label, where I was shocked to see it’s the cheap ethanol stuff that used to be orange. This change in practice is going to create mass confusion, since you can’t go by color anymore. You need to read the label if you care about keeping denaturants out of your potable tanks and/or ethanol away from your seals and impellers.

When I got home I checked the label of some leftover pink stuff from West Marine. It has no ethanol, as expected (PG only), but the label also says it has corrosion inhibitors. So green EG antifreeze is not the only way to get that.

 

[pdqaltair]

... as expected (PG only), but the label also says it has corrosion inhibitors. So green EG antifreeze is not the only way to get that.

Sort of true. There is a limited anti-corrosion package, but nothing like engine coolant. But good enough for winter.

The folks that use the cheap stuff or even worse, vodka, don't get even that.

 

[TakeFive]

Regarding those who avoid antifreeze by “blowing out” your” lines with a compressor, make sure you know what you’re doing. Air is a very poor pushing fluid due to low viscosity and density. It will channel past the water at low points, and will not push uphill. You need to drain low points, though getting to the fittings can be near impossible. And if you can drain all the low points, there’s really no need for a compressor.

If you know where every low point is and can access and drain every one of them, then go for it. But the pink stuff followed by a thorough multi-stage rinse looks good compared to all those headaches.

 

[Maine Sail]

I picked it up and checked the label, where I was shocked to see it's the cheap ethanol stuff that used to be orange. This change in practice is going to create mass confusion, since you can't go by color anymore.

You should not go by color, don't really know where that came from? We used to use Pahnol, which is an excellent PG product. Pahnol was always on the orange side. Always read the label.

 

[Minnewaska]

Regarding those who avoid antifreeze by "blowing out" your" lines with a compressor, make sure you know what you're doing........

It takes much more discipline that some have. It's not a simple process, nor very quick. I'd say it takes me at least an hour.

First, I drain the water tanks as best I can, then close all the valves to allow the compressed air to create pressure and not backflow. Then I drain the system via the hot water heater, which is the absolute low point in the bilge. We have a city water hook up, which is where I attach the compressor and it's actually at the high point in the system. Going around and bleeding each faucet, sequentially takes time. Pull the shower faucets out straight to drain. At first, there is a little spitting you'd want to believe is empty, because it's already taken so long. However, give it proper time and it will eventually blow dry. I'm sure there is a tablespoon of water here and there. As long as it's not filling a low spot, it won't burst the line, when it freezes. Most of our onboard lines are Pex, so no dips anyway.

I spent too much time as a kid with foul disgusting fresh water supplies. Back then it was common to dose the water with foul stuff, in the name of sanitation. Gross. Our water looks and smells like it came out of the faucet at home. No chemicals going in the system, other than a chlorine shock at the beginning of the season, that is flushed out.

 

[Maine Sail]

Regarding those who avoid antifreeze by "blowing out" your" lines with a compressor, make sure you know what you're doing.

Yes, hardly a spring goes by where we are not called in to fix freeze/split issues from owners who blew out lines. This is exactly why the vast majority of boat yards do not blow out lines and instead use PG. The key is to only run it through the piping and not pour it directly into the tanks.

Freshwater System Winterizing

 

[Minnewaska]

By all means, if you can't figure out how to blow the lines out correctly, resort to dosing up your lines with anti-freeze. However, blowing them out isn't rocket science. Of course, most tasks are not attended to with any sense of responsibility by boat yards. I'd never have them blow out the lines. I have four heads, a transom shower, a washing machine and dishwasher and have never had a freezing issue with any. Use your noodle, or use the goo. You'll never see chemicals used to store our potable water system.

I filter the water off the dock, before it goes in our tanks too. Bad boat water sucks.

 

[rschudy]

Two chemicals are used to lower the freezing point of water in "permanent" antifreeze - ethylene glycol and propylene glycol. Ethylene glycol is used in the green antifreezes. It is both sweet and quite toxic. Ethylene glycol has a serious problem when used as an antifreeze, which is that it gradually forms a gum that coats or plugs the cooling passages, so ethylene glycol antifreeze needs to be flushed and replaced every few years. Ethylene glycol antifreeze is obsolete. For example, Yanmar does not approve using it, and using it could void a warrantee. You may have noticed that the antifreeze for modern cars is pink. Pink is an international standard color for substances that are not very toxic. Pink antifreeze is made with propylene glycol. You may have noticed newer pink antifreezes advertised as good for 150,000 miles. These are modern propylene glycol antifreezes. The antifreeze used to winterize RVs and boats is also pink, because it is nontoxic; it is also made with propylene glycol. Propylene glycol is a permitted food additive; for example, it is added to shredded coconut to keep it moist. As other posters have indicated, winterizing antifreeze should not be used in closed loop cooling systems, because it lacks the corrosion inhibitors, water pump lubricants, and other additives that engines need. One sure way to select your closed-loop antifreeze is to check what your engine manufacturer recommends. When I did this for Yanmar, I encountered four tested and approved brands, all based on propylene glycol.