RV Antifreeze Testing.

[JohnnieMo]

So for a few seasons I've been wanting to run a test on the RV antifreeze many of us use in our boat engines. I've had a theory that the antifreeze dilution was not as significant as most people thought.

So for my test I mixed RV antifreeze at ratios of 20%, 40%, 60%, 80% and 100%. The product itself is rated as "burst proof to -50C"

Here are the results from my testing this week at -25C



In every dilution the vessel survived (glass jars) except in the case of 0% (water).

In every dilution the product was no longer a liquid. It got progressively harder as the dilution decreased. Surprisingly even at 100% the product was an immovable "slush". I didn't expect that.

It appears that the RV antifreeze becomes a gel even at warmer temps. However it prevents expansion and that is what matters most.

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So what's the take away? Well even at these frigid temps I think even a 50/50 mixture would keep your boat safe. If it doesn't get this cold where you are I think you could run in antifreeze without draining your block and be fine.

[bsreid]

My take away, move somewhere warmer Was in Calgary yesterday and oh boy was it ever cold.

I’m surprised it went slush at only -25, but I guess slush is fine as long as it doesn’t expand to much.

[chpthril]

What the "-#C" labels on the jars represent? Is that the freeze point indicated by a PP hydrometer?

The slush is how the A/F is designed to react, so thats normal.

My takeaway, im going to still suggest people drain the system of water, prior to introducing A/F. Your test shows it works best at 100%. No way to predict what ratio one might end up with, if they just induce the A/F into en engine full of water.

Thanks for doing this test. Good info.

[KoolAid]

Excellent information and test!

[JohnnieMo]

@CHP

I initially made an assumption that the rating on the jug implied that a full concentration would not expand (I.e remain liquid) until -50C. So I then assumed the as I added water to the mix the "freeze" temp would increase linearly. So a -20C rating would be 3/5 water and 2/5 antifreeze. My assumption was the vessel would burst at -20C. That did not happen. It seemed that even a marginal presence of antifreeze would prevent bursting.

I do have a hydrometer somewhere but I assumed that it would only work for engine coolant. I could be wrong.

The take away is my labels are useless.

FWIW I had a jug of 50/50 dexcool sitting outside and it was perfectly liquid the entire test.

You'll have to wait for my Youtube video for all the fun facts!

The good news about Calgary is even though we had a week of this crap, it was well above freezing for most of this polar vortex.

[chpthril]

You can use a hydrometer, just needs to be one for polypropylene and not ethylene glycol one.

[freeheel4life]

We use a Camco refractometer along with the Camco antifreeze. When you look thru the window to test it shows two number. Slush point, and burst point. Ive gotten roughly the same results as you Johnny but not trying or collecting data. Had a 5 gallon jug of -50F while skiing and it turned to slush(overnight lows were about -4F) and saw zero expansion of the plastic container.

Great test and great data. Thanks for doing it!! Heres the refractometer we use if anyone is interested.

https://www.amazon.com/Camco-65401-R.../dp/B0000AYH03

[giers]

My take away, move somewhere warmer Was in Calgary yesterday and oh boy was it ever cold.

I’m surprised it went slush at only -25, but I guess slush is fine as long as it doesn’t expand to much.

-28 today.

[Brianrzr]

What kind of time frame were they exposed to that temperature?

[JohnnieMo]

That is overnight. However they altered state in about 2 hours @ -25C.

[BrentP]

So, is the general consensus that an engine would survive the antifreeze turning into Gel like this? We just dont want it to expand and crack the block? Looking at the 20% picture, seems like youd want to make sure you flush the motor twice to stay away from even that level of solidification if you live in a climate like this?

Also, Brrrrrrr

[JohnnieMo]

RV Antifreeze Testing.

Yes the engine would survive (my boat is 5 feet away from this test and mixed at the 100% concentration). The antifreeze is supposed to turn into a gel. The antifreeze must be designed to limit expansion and not prevent "freezing".

[talltigeguy]

To add just a little controversy, there are plenty of people who are very confident that antifreeze is not necessary. A proper draining is all your block should need. Just make sure to get the heater core blown out properly.

[bsreid]

^^That is very true. Is that not how the come from the factory and get shipped up north to sit outside? So obviously everything would be ok. No water no freeze. Antifreeze just prevents rust and is a backup just in case of missed water, correct?

[lee]

^^That is very true. Is that not how the come from the factory and get shipped up north to sit outside? So obviously everything would be ok. No water no freeze. Antifreeze just prevents rust and is a backup just in case of missed water, correct?

Correct, it slows down the corrosion of the inside of the block.