How much Marine antifreeze to winterizing engine?

[BoatBumm]

Be aware that there are commonly two different types of “cheap” pink antifreeze. The cheapest is mostly methanol or ethanol with a dollop of propylene glycol. The somewhat more expensive version is just the opposite - mostly propylene glycol with no or very little methanol. In my area the cheaper ethanol/methanol stuff is $2-3/gallon, the premium version about $6-7/gallon. Although being a name brand drives the price up. Prestone RV/Marine Waterline antifreeze is the cheap ethanol stuff at a premium price. Although Prestone also sells a “-100 degrees” version that is just water & propylene glycol. And for me the mostly propylene glycol stuff is harder to find. Stores mostly stock the cheaper methanol stuff.

Many plastics and “rubbers” used in marine pumps and filters do not like methanol, especially bathed in it for the many months of winter storage. The “rubber” used in water pump">raw water pump impellers is a good example. The methanol can damage the vanes. The usual advice is to remove the rubber impeller once the engine is winterized so that the vanes don’t sit in one position for months. I give mine a final rinse in fresh water to rinse off the antifreeze before storing the impeller away for spring.

But propylene glycol can be bad for some materials too. Practical Sailor has reviewed this. If I recall correctly the neoprene “rubber” used by Jabsco for their tricuspid joker valves doesn’t like either propylene glycol or methanol, and PS advised using the environmentally toxic ethylene glycol (the engine stuff) in a head with a Jabsco joker valve since that antifreeze is going into a head with a holding tank that should get pumped into a sewage treatment system and not into the environment.

And the plastic filter bowls in many potable water systems don’t like various types of antifreeze.

So do your research into the pumps and filter bowls your boat has and what the antifreeze compatibilities are.

[David Mathis]

If you have anti-freeze (coolant) in the engine and you're only winterizing the heat exchanger, running the engine until pink comes out of the exhaust is probably alright. However, if you have raw water cooling, the thermostat will be closed and the pink winterizing liquid will bypass the engine and go out the exhaust manifold. Warm the engine first? What happens when the cool pink hits the thermostat? It closes and the pink bypasses the block then leaves through the exhaust manifold. The way to winterize a raw water cooled engine is to drain the block and manifolds (easy on some engines, not so easy on others) then fill the block with the pink, often through the upper coolant circulation hose which is attached to the coolant circulator pump. After filling the block with pink, attach a hose to the water intake, drop it into the bucket of pink, and run the engine until the pink comes out of the exhaust. By using this method, the winter pink isn't diluted and will protect the engine even if it gets cold enough to solidify (freeze). The pink, unlike water, does not expand when it freezes so, unless it's diluted, will not crack the block when the temperature falls. This method has worked for many years in Upstate New York where the temperature occasionally falls to -20 or colder.

[JBsurfin]

Originally Posted by vpbarkley

I plan to place the engine raw water inlet hose into a bucket containing pink, RV/Marine antifreeze.

Then idle the engine until pink antifreeze comes out of the exhaust, looking full strength or undiluted.

Approximately how many gallons of antifreeze will this take?

The engine is a 4 cylinder Yanmar with a typical wet muffler.

There are hard freezes here in Maryland.

Thank you for your input.

Being in NJ, I too buy the pink -50 RV-Marine antifreeze from walmart at 2.70 a gal. Been using it for years and never had any freeze issues, even with 2 week long -30 one winter. I go through 6 gals for the engine and another 3 for the water system. At 2.70 a gal, I can afford to go extra to flush out.

[Free2Sail]

This is slightly off-topic, but I'm curious how much the freezing equation changes if the boat is wintering in (sea)water? In the Northeast, with bubblers under the docks, average winter seawater temps in the high 30s-low 40s F... Before this season, the boat always wintered on the hard.

We usually run pink -50F AF through the raw water intake, heads, and the water system, draining and closing off the water heater with a bypass valve, as it takes another 5 gal. One season we blew the water out of the whole water system with a compressor, with seemingly no adverse effects, but it seemed like a lot more work. Thoughts on draining/blowing out the water system vs filling it with AF? Some folks have also advised using the cheapest vodka instead... For the water system, I mean.

[rslifkin]

Personally, I always flush my water system with antifreeze. There's enough plumbing that if I blew it out, I wouldn't be confident that I won't end up with a puddle of water settling into a low spot at some point.

If you use antifreeze in the water system, make sure it's at least the -50 stuff and don't let it get diluted. If it's diluted too much, it becomes food for anything that wants to grow in there, while a high enough concentration will kill any slime, etc. in the lines. And don't blow it out after, leave the lines full of antifreeze. Getting it all out in the spring is much easier when it's not dried onto the walls of the pipes / hoses. I just end up flushing a couple hundred gallons through the whole system in the spring to reach the point where I'm good and happy with it.

[lewisa]

I typically use 2 gallons of -50 pink antifreeze to winterize my Perkins 4-108 with waterlife muffler. No problems in 40 years in Michigan and Maine. I just confirm that the "pink" came out the exhaust.

[BoatBumm]

Practical Sailor has come down hard against using vodka, cheap or otherwise, for winterizing potable water systems. Saying it doesn’t work well and strongly promotes smelly bacterial growth. Use the pink stuff instead.

[thinwater]

Originally Posted by altinr

... The reason you don’t want to use Ethlene glycol standard antifreeze Is that it is toxic to wildlife!

Read the thread above. Toxicity to marine life is urban legend pushed by the folks that make PG. Toxicity to wildlife (cats, dogs, rabits) is only a factor if you were planning on leaving open containers lying around or dumping it and making an obvious puddle. But why would you do that? Makes no sense. Just use EG responsibly.



Of course, Never use EG in potable water systems. The best, and really only argument for using PG throughout, is that people can make mistakes. Many slept through chemistry class, or made a concerted effort to forget it all.

[thinwater]

Originally Posted by BoatBumm

Practical Sailor has come down hard against using vodka, cheap or otherwise, for winterizing potable water systems. Saying it doesn’t work well and strongly promotes smelly bacterial growth. Use the pink stuff instead.

The thing about vodka is that people think you can add just a little. In fact, you need to achieve an alcohol concentration of 25% to prevent fermentation, which means about 60% vodka. Yes, I have tested this. That's a lot. Any less than that and it will ferment, just like wine. Imagine filling your lines with wine. Ugh.



Better RV antifreezes include corrosion protection packages (which vodka does not). These also have some inhibiting effect on fermentation (they are alkaline).


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Cheaping out on AF is one of the best ways to screw up the potable water system, making it unsuitable for drinking. It's not that hard to keep a clean water system, but you need to follow the rules of nature.

[vpbarkley]

The feedback has been terrific and eye opening. What a convoluted problem.

For the fresh water system and head I'll drain and vacuum or blow the water out.

For raw water and heat pumps I'll use regular Prestone ethylene glycol antifreeze.

I'll keep the antifreeze away from all strainer bowls.

[goboatingnow]

I’ve never seen such a nonsense convoluted thread

I dilute 3:1 cheap EG stuff I can find , this gives me protection to -20 C. I have a bucket with a tap and a hose. Shut the intake Open the strainer , start engine , feed in the bucket. Shut the engine.

There’s no thermostat in indirect raw water cooling

For potable water I just drain out from the low point drain

I change the closed circuit system every few years and check the anti freeze effectiveness with a meter

[zstine]

Wow, I am amazed at how many people use Ethylene Glycol! Really, WHAT? you do know it is Illegal in many (most?) states to dump EG overboard and it is really bad for the environment. so if you winterize your engine with it.. How do you catch it when you start the engine in the spring? Pay the extra $1 per gallon for the pink stuff!!

[zstine]

Originally Posted by thinwater

Read the thread above. Toxicity to marine life is urban legend pushed by the folks that make PG. Toxicity to wildlife (cats, dogs, rabits) is only a factor if you were planning on leaving open containers lying around or dumping it and making an obvious puddle. But why would you do that? Makes no sense. Just use EG responsibly.
.

So how do you prevent it from splashing/puddling on the ground when you fill your boat's raw water system? You don't run the antifreeze through until it comes out the exhaust? How do you use EG responsibly???

My neighbors dog died from drinking EG that was left on the driveway after he changed his car's antifreeze and did a messy job. That stuff is poison! But I have had several pinkish glasses of water in the spring b/c I didn't flush the system well and I've had no issues. Yeah, not scientific, but I call BS on your claim that EG is not toxic. If it kills dogs, it can kill aquatic life too.

[rslifkin]

Originally Posted by zstine

So how do you prevent it from splashing/puddling on the ground when you fill your boat's raw water system? You don't run the antifreeze through until it comes out the exhaust? How do you use EG responsibly???

My neighbors dog died from drinking EG that was left on the driveway after he changed his car's antifreeze and did a messy job. That stuff is poison! But I have had several pinkish glasses of water in the spring b/c I didn't flush the system well and I've had no issues. Yeah, not scientific, but I call BS on your claim that EG is not toxic. If it kills dogs, it can kill aquatic life too.

EG is toxic to mammals, that doesn't necessarily mean it's equally toxic to everything. And both EG and PG biodegrade, so if sufficiently diluted in water until then, the concerns are far lower.

I'd definitely be very careful of using EG if winterizing on land and make sure you don't let any get spilled. So you'd have to rig a careful catch setup for whatever is going to get discharged in the process.

Personally, I've been just winterizing everything with PG, but I also winterize everything except the bilge pumps before we haul out. I hate having to start engines and such on land, so I always schedule our haul out to make sure I'll be able to do everything in the water. Generally I plan with the yard to be the first boat of the day on haulout day, so we winterize everything except the engines in the slip the weekend before, then move the boat for haulout the night before and winterize the engines once we arrive in the lift pit.

[thinwater]

Originally Posted by zstine

Wow, I am amazed at how many people use Ethylene Glycol! Really, WHAT? you do know it is Illegal in many (most?) states to dump EG overboard and it is really bad for the environment. so if you winterize your engine with it.. How do you catch it when you start the engine in the spring? Pay the extra $1 per gallon for the pink stuff!!

Read the entire thread, including links to environmental data. Read the SDSs. You have poor information. Your illegality statements are false. The funny thing is that I have spoken to many state regulators, and they simply copy web info from others, without confirming factual correctness.


The EPA studies of EG and PG deicer found no difference in environmental impact. Read them. Read the SDSs. We are NOT trying to avoid expense. PG is actually WORSE for the marine environment, because the COD per unit freeze protection is higher.



If you can find quantitative data supporting higher marine toxicity of PG, post it. Not internet crap. Quantitative studies.



You have been green washed (sold false green information). It is common.