So I did a 50-50 mix with zerex the green, if it matters. Anyway the lowest I got  was -22. How do you folks protect your eng. in negative weather like that?

run of the mill 50-50 and block off the radiator.  Never had an issue.

I only use Cat ELC  (Extended Life Coolant) coolant in everything I service,  premixed at 50/50 BUT   Cat also do neat ELC for bringing the % back to where it needs to be if someone has put water in the system OR the freeze temp  needs to be lower, they also do a conditioner to add after a coolant sample has come back from the lab with bad results, it very rarely needs to be changed in Heavy Plant equipment partly because you're very lucky not to have a real good coolant leak every once in a while due to the conditions 

Here in the Midlands UK -20C is more than enough so 50/50 is ok, It's in my truck, sampled at service time, been in 3 or 4 years now and no problems on the samples

@wil440, what do you use to test the engine coolant's condition?  I've been using these  

  On 12/23/2022 at 5:19 PM, IBMobile said:

@wil440, what do you use to test the engine coolant's condition?  I've been using these  

I use the UK Cat dealer  " Finning same as Canada" oil sample lab as I have to oil and coolant sample every machine I service so always have the sample kits at hand

 

But the kit you use has PH so that's ok, thing with Cat ELC is  if it is bright and clear red it is ok when it gets to be not bright and clear is when it needs changing and this is reported by the lab so I already have a good idea once it's in the sample bottle of what the outcome will be

I do also have the sample point connector and the sample vac so I have no problem getting a sample of any fluid but coolant you would just syphon enough into the bottle with the supplied clean new tubing and drop it either in the post with the supplied paid for label or here you can drop it into Finning depot in the paid for bag, pretty sure a coolant sample kit here is £18

 

44 years plus I've been using Cat SOS oil/coolant sampling and not once has it been wrong unless I've introduced something foriegn into the fluid but the lab will ask for a resample if any doubt, beari ng in mind the conditions of heavy plant sometimes fluids can get contaminated but never on my truck as the conditions are cleaner

I will add that here in the UK Cat ELC is £60 ish for 4.4 UK Gallon  or  5 US Gallon drum from Finning the UK  Cat dealer

  On 12/22/2022 at 6:13 PM, jlwelding said:

the lowest I got  was -22. How do you folks protect your eng. in negative weather like that?

That's likely the point at which your coolant may turn into a Slurpee, not the point at which it turns into an ice cube. So as the Slurpee gets icier and icier, the remaining liquid is a higher percentage of anti-freeze, thus eventually is protected from further freezing.

  On 12/26/2022 at 4:18 PM, LorenS said:

That's likely the point at which your coolant may turn into a Slurpee, not the point at which it turns into an ice cube. So as the Slurpee gets icier and icier, the remaining liquid is a higher percentage of anti-freeze, thus eventually is protected from further freezing.

When antifreeze is used in a coolant system as the temperature drops to around the protection point which for Cat 50/50 is around -37C the antifeeze makes it harder for the H20 molecules to join together and form crystal lattices or ice, no water in a antifreezed system seperates out to form ice therefore there is no concentrated antifreeze, it is all at the mixture ratio that was added whether thats 30/70, 50/50, or 70/30  or neat, at some point the whole lot will freeze, it is physically  impossible for water to seperate out and freeze, and if it was possible wherever that ice was to form it would have the ability to split parts so there would be no point in antifreeze in the first place, lets say 1 radiator tube had a portion where the water seperated, it would just split that tube

Now we getting to the meat and potatoes of antifreeze. I often wondered about how well it mixes.

Here is a chart to help visualize freeze point to mixture percentages.

  On 12/27/2022 at 5:41 AM, IBMobile said:

Here is a chart to help visualize freeze point to mixture percentages.

Yes that's the chart   50/50 is -37C  so how cold some of the USA has been recently you'd want 60/40 to 70/30  with the very ideal at 65/35

  On 12/27/2022 at 3:44 AM, jlwelding said:

Now we getting to the meat and potatoes of antifreeze. I often wondered about how well it mixes.

It's mixed and never "unmixes"  doesn't mean it won't freeze though 

Ok here in south Tx it gets really hot 108 - 110 heat index 115. so what mixture am I looking at for keeping it cool? 50 - 50?

Yes 50/50 but the wetting properties are more important to you, basically there's an additive in antifreeze/coolant that alters the surface tension of the coolant a bit like dish washing liquid and water, once the surface tension is changed by the additive it stops it clumping into little beads it just spreads which means the coolant can remove more heat than just plain water

I'd just use Cat ELC if you have a local source, fill and forget, Cat dealer in Texas is Holt Caterpillar, spent a month in the Cat shipping facility in Waco repairing brand new backhoes with one field service guy from Holt 8 years or so ago

  On 12/27/2022 at 3:45 PM, jlwelding said:

so what mixture am I looking at for keeping it cool? 50 - 50?

A simple answer is yes, a 50/50 mix will work for your location in Texas.  As the concentrate of antifreeze is increased the boiling point is increased but the drawback to that is at higher concentrations the ability of the coolant mixture to absorb and release heat is reduced.  I experienced this in 1986 when a customer's car was running hot/overheating all the time.  After talking to him he said that he had "flushed "the cooling system and fill it with 100% antifreeze.  After draining and refilling the cooling system with a 50/50 mixture of antifreeze the overheating problem was fixed.  

 

The other import part of the cooling system to increase the temperature at which the engine coolant will boil is the system pressure cap.  The higher the pressure the higher the boiling point.  For every PSI increase in pressure the boiling point is raised ~2.5°F (1.39°C). There for an OEM radiator pressure cap rated at 16 PSI will raise the boiling point to 252°F (122.24°C).  Do not go above the vehicle manufactures recommended pressure or failure of other cooling system components will occur.  

 

 

 

I design quite a few underfloor heating systems for slaughterhouse blast freezers and while not an expert on the minutia (W-T of the glycol world I am not!), I am relatively familiar.  Here are two documents I have saved to the reference library I have on my laptop.

This document is for Propylene Glycol but is provided as it's from DOW Chemical Company.  See Page 9.
https://www.dow.com/documents/en-us/app-tech-guide/180/180-01286-01-engineering-and-operating-guide-for-dowfrost-and-dowfrost-hd.pdf

 

This document says the same for Ethylene Glycol and is from a Union Carbide Chemical company.
https://www.magnumsolvent.com/productdata/Product Literature/Heat Transfer Fluids/Norkool Burst vs. Freeze Protection.pdf

Basically if I'm wrong, then so is DOW and Union Carbide, and that's pretty good company to keep.

The links are for underfloor heating fluid not vehicle antifreeze like ELC