# Antifreeze: Propylene glycol vs. ethanol type



## TakeFive (Oct 22, 2009)

The previous owner left me with 3 1/2 gallons of antifreeze for me to use winterizing my boat. The bad news is it is the red Walmart RV type (actually it's Camco brand), which uses denatured ethanol instead of propylene glycol. I've never been a fan of this type of antifreeze for a variety of reasons. I've always used the propylene glycol purple stuff (good to -60F).

I would rather not just throw out the ethanol based stuff, so I'd like to find a place I can use it where it will cause the least harm. I'll use the purple stuff for the rest. I remember a Practical Sailor test where they said the ethanol antifreeze can mess up rubber seals and valves in the head, so I won't use it there. But for the other parts of my boat (raw water cooling system, 2 fresh water tanks and associated tubes and faucets) where would be the least harmful place to use the ethanol antifreeze?

I realize that the previous owner probably used the ethanol in everything, so what additional harm can come from using it again this year? But then, maybe that explains why he also left a rebuild kit for the head. Perhaps the ethanol messed up the seals.


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## pdqaltair (Nov 14, 2008)

I'd just pitch the ethanol stuff. Perhaps you could "get away with it" somewhere, but not enough to conclude it has a positive value. I has the potential to damage elastomers in every system. It's cheap junk, not worth carrying home.

Pitch it. And I do NOT mean recycle it. I designed one of the largest glycol recycling plants in the US (probably services your area), and ethanol is NOT recyclable with glycol. Another reason not to use ethanol. [I no longer work there, but this is true of ALL recycling plants in the US--I chaired the trade association for many years.]


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## overbored (Oct 8, 2010)

yes get rid of it. it is poisoning and should never be used to winterize. propylene glycol is edible, ever eaten a popsicle then you know it is edible. and won't harm the environment. the EG may have been used in the engine as coolant. if so use it there , never mix the two.


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## Minnewaska (Feb 21, 2010)

Horrible stuff, I'm on the side of pitch it out. 

Also, I stopped putting anti-freeze of any kind in my fresh water tanks many years ago. Just hook up a little compressor to the system and blow the lines out now. The cheap little compressor was the cost of a few years of anti-freeze anyway. You can get all sorts of tire valve stem adapters to connect to intake hoses. I actually have one that screws into the city water inlet (which is the only purpose I ever use that port for). Even better if you just fashion a compressor hose with a barb coupling into your system, instead of the quick connect.

My fresh water always tastes fully normal now, it's cheaper and I'm dumping less a/f into the water. I may be more sensitive than others, but I can taste the funk from anti-freeze, even when it claims to be tasteless and is well rinsed out. Hate it.


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## TakeFive (Oct 22, 2009)

overbored said:


> yes get rid of it. it is poisoning and should never be used to winterize. propylene glycol is edible, ever eaten a popsicle then you know it is edible. and won't harm the environment. the EG may have been used in the engine as coolant. if so use it there , never mix the two.


I'm a little confused by your post. Ethanol and EG are totally different chemicals.

EG is used in my engine as coolant, as is true for most closed-loop systems.

I would strongly advise others who read this to NEVER use the ethanol based antifreeze as engine coolant. That could very possibly lead to an explosion.


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## travlin-easy (Dec 24, 2010)

When I was a kid, denatured alcohol was used as an engine coolant. But, back then, engines didn't run as hot as they do today. 135 degrees was about as hot as my old 1951 flathead Ford got, and that was on a mid summer day.

Gary


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## pdqaltair (Nov 14, 2008)

overbored said:


> yes get rid of it. it is poisoning and should never be used to winterize. propylene glycol is edible, ever eaten a popsicle then you know it is edible. and won't harm the environment. the EG may have been used in the engine as coolant. if so use it there , never mix the two.


For the record, ethanol may be denatured with many things, depending on the application. For solvent use, acetone is common, as is kerosene. There are over 100 listed chemicals. But for a potable application they used denaturants that are distasteful but not truly toxic. Bitrex for example. Common sense. Otherwise they could not recommend it for RVs.

I also like EG for the blackwater system. It is better for the neoprene parts, and no one will drink that. Biodegradeability and marine toxicity is the same for PG and EG. Read the MSDSs.


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## pdqaltair (Nov 14, 2008)

Minnewaska said:


> Horrible stuff, I'm on the side of pitch it out.
> 
> Also, I stopped putting anti-freeze of any kind in my fresh water tanks many years ago. Just hook up a little compressor to the system and blow the lines out now. The cheap little compressor was the cost of a few years of anti-freeze anyway. You can get all sorts of tire valve stem adapters to connect to intake hoses. I actually have one that screws into the city water inlet (which is the only purpose I ever use that port for). Even better if you just fashion a compressor hose with a barb coupling into your system, instead of the quick connect.
> 
> My fresh water always tastes fully normal now, it's cheaper and I'm dumping less a/f into the water. I may be more sensitive than others, but I can taste the funk from anti-freeze, even when it claims to be tasteless and is well rinsed out. Hate it.


I'm betting the reason you can taste the funk is that you did not use quite enough. If diluted at all it can ferment over the winter and get like Boone's Farm. Very common problem, particularly if it was put in the tank instead of just the lines. Strong enough, never a problem.


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## TakeFive (Oct 22, 2009)

Minnewaska said:


> Horrible stuff, I'm on the side of pitch it out.
> 
> Also, I stopped putting anti-freeze of any kind in my fresh water tanks many years ago...I may be more sensitive than others, but I can taste the funk from anti-freeze, even when it claims to be tasteless and is well rinsed out. Hate it.


I'm leaning toward pitching it, unless someone else comes up with a compelling but harmless use for it.

I used the purple propylene glycol stuff in my old boat for 6 winters. Every spring I'd rinse everything out, then do an overnight shock with chlorine, followed by a purge. The water always looked and smelled clean. I'd brush my teeth with it, but would not swallow it. We used bottled water for drinking on the boat. However, it was good to know that it was pretty good in case I had to swallow it in an emergency (like losing my bottled water due to a leak or something).

Since the ethanol antifreeze was left behind on this boat, it's a good bet that the previous owner used it to winterize before. Like I did before, I rinsed the tanks out, and did overnight chlorine shocks followed by purge TWICE. I would not call the water vile, but it is definitely is not a clean as my old boat (yet). Even after going through a few tank fulls this year, the water has a bit of alcohol smell to it, and after sitting for a week it comes out of the faucet foamy for the first 10 seconds or so. So there's still some undesirable stuff in the tank or lines. It's good enough for washing hands, etc., but we're definitely not drinking it.

I'll consider using a compressor to evacuate the system in future years, but for this year I'm going to drain as well as I can then load up the system with purple propylene glycol. Since it worked on my old boat and always rinsed clean, I'm hoping that soaking my lines, pumps, and valves with the same stuff all winter might remove the last traces of previous owner's antifreeze, and then rinse clean in the spring.

We'll see if it works.

I like the idea of using EG in the head and holding tank. That's on the list now.


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## Minnewaska (Feb 21, 2010)

pdqaltair said:


> I'm betting the reason you can taste the funk is that you did not use quite enough. If diluted at all it can ferment over the winter and get like Boone's Farm. Very common problem, particularly if it was put in the tank instead of just the lines. Strong enough, never a problem.


I've never heard of a glycol product fermenting. Interesting. You mean some type of bacteria consume it? All old plumbing has some kind of contamination inside, even on land. I wonder if there is an interaction.

I'm not sure my experience has been a lack of product, since the tanks were emptied first, then it was run through all the lines, until water was fully displaced and color was bright. Conceivably, there was little in the tank. I always had the feeling that the plastic hoses were permeated with the stuff over time, but that was just my imagination.

Nevertheless, blowing the system out with air is less expensive over time and fouling is a non issue. It just occurred to me that the last time I used antifreeze, we had one head, transom shower and a galley sink and it took a few gallons. With two fresh water tanks, three heads, two dedicated showers, galley sink and washing machine, the compressor had to pay for itself in defrayed antifreeze costs the first year!


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## MastUndSchotbruch (Nov 26, 2010)

Minnewaska said:


> Horrible stuff, I'm on the side of pitch it out.
> 
> Also, I stopped putting anti-freeze of any kind in my fresh water tanks many years ago. Just hook up a little compressor to the system and blow the lines out now. The cheap little compressor was the cost of a few years of anti-freeze anyway. You can get all sorts of tire valve stem adapters to connect to intake hoses. I actually have one that screws into the city water inlet (which is the only purpose I ever use that port for). Even better if you just fashion a compressor hose with a barb coupling into your system, instead of the quick connect.


What do you do about the pumps? I would not be too much concerned about the lines anyways since they are usually rubber hoses. But residual water freezing in a pump would be a problem, non?


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## Minnewaska (Feb 21, 2010)

MastUndSchotbruch said:


> What do you do about the pumps? I would not be too much concerned about the lines anyways since they are usually rubber hoses. But residual water freezing in a pump would be a problem, non?


Only one fresh water pump, with quick connects on inlet and outlet. I disconnect and let drain. Fully dried long before sustained freezing temps.

I run antifreeze through all other raw water pumps aboard.


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## MastUndSchotbruch (Nov 26, 2010)

Minnewaska said:


> Only one fresh water pump, with quick connects on inlet and outlet. I disconnect and let drain. Fully dried long before sustained freezing temps.
> 
> I run antifreeze through all other raw water pumps aboard.


Yeah, I guess if you have quick connects on it and it is easily accessible, that is an option. Not sure I want to fold myself into the space under the sink and mess with hose clamps, in my case.


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