---
title: 'How to Test Your Coolant for Winter (Before Major Damage is Done)'
source: 'https://youtube.com/watch?v=29z94xBdAjE'
video_id: '29z94xBdAjE'
date: 2026-08-05
duration_sec: 1166
---

# How to Test Your Coolant for Winter (Before Major Damage is Done)

> Source: [How to Test Your Coolant for Winter (Before Major Damage is Done)](https://youtube.com/watch?v=29z94xBdAjE)

## Summary

This video demonstrates how to test and maintain the correct 50/50 antifreeze-to-water ratio in a car's cooling system to prevent freezing, overheating, and corrosion. The host explains the science behind coolant, shows a freeze test with pipes, and provides a step-by-step guide to testing and adjusting coolant levels.

### Key Points

- **Importance of Coolant** [00:02] — Coolant prevents freezing, overheating, and corrosion. It is a mix of antifreeze and distilled water.
- **Boiling Point Differences** [00:42] — Water boils at 212°F, 50/50 coolant at 226°F. Pressurized systems raise boiling points further (e.g., at 15 psi, water boils at 250°F, coolant at 260°F).
- **Corrosion Prevention** [01:22] — Antifreeze contains corrosion inhibitors; using straight water leads to scale and rust, damaging components like water pumps.
- **Freezing Point Protection** [02:14] — Water freezes at 32°F, 50/50 coolant at -34°F. Freezing can crack engine blocks.
- **Freeze Test Demonstration** [02:52] — Pipes filled with 50/50 antifreeze and plain water were left outside in freezing weather. The water pipes burst, while the 50/50 pipes remained intact.
- **Freeze Plugs Explained** [04:30] — Freeze plugs are casting plugs, not designed to prevent freezing. They can pop out if coolant freezes, but relying on them is not recommended.
- **Tools Needed** [05:19] — Antifreeze tester (hydrometer), funnel, antifreeze, and distilled water. The tester costs about $5.
- **Testing Procedure** [07:35] — Ensure the cap is cool, extract a sample, fill the tester to the line, tap to remove bubbles, and read the freezing point. Aim for -34°F (50/50).
- **Calibration Check** [09:50] — Test the hydrometer with distilled water (freezing point 32°F) to verify accuracy.
- **Cost-Effectiveness** [11:09] — Testing takes less than a minute and costs under $5, potentially saving thousands in engine repairs.
- **Washer Fluid Winter Mix** [11:22] — Summer washer fluid may not protect against freezing; replace with winter mix (good to -25°F) and flush the system.
- **Correcting Ratio in Jaguar** [12:40] — The Jaguar had a head gasket leak, leading to diluted coolant. The host drained the radiator and calculated the needed antifreeze to restore 50/50.
- **Calculating Antifreeze Needed** [15:33] — Using the cooling system capacity (8 quarts) and current concentration (25% antifreeze), the host determined to add 2 quarts of full-strength antifreeze.
- **Adding Antifreeze** [16:40] — Added 2 quarts of concentrated antifreeze, then topped off with 50/50 mix. Used a spill-proof funnel and adapters.
- **Bleeding Air from System** [17:21] — Ran the engine with heat on to open the heater control valve, allowing air bubbles to escape. Topped off coolant as needed.
- **Final Verification** [18:40] — After bleeding, took a sample and confirmed the freezing point was -34°F, indicating a proper 50/50 ratio.

### Conclusion

Maintaining a 50/50 antifreeze-to-water ratio is crucial for protecting your engine from freezing, overheating, and corrosion. Regular testing is quick, inexpensive, and can prevent costly damage.

## Transcript

time of the year again the leaves are falling it is starting to and that means winter is right around the corner so today i'm going to show how to check and test your coolant in your car that way
your engine doesn't freeze it doesn't crack your cooling system doesn't burst and you have nice warm heat all winter long inside the cabin of your car so you now for those who are lucky enough to live in an area that doesn't get cold in
applies to you and here is why so coolant is a mix of antifreeze and distilled water and it does three main things it prevents your engine and cooling system from freezing overheating and from corroding so the
your cooling system from boiling and overheating boiling cool well the air in the water doesn't cool doesn't have good heat transfer the fluid in our cooling system to boil if we take a look
right here you can see our water is boiling but our antifreeze is not under normal conditions water boils at 212 degrees fahrenheit and 50 50 coolant boils at 226 degrees fahrenheit now cooling systems are pressurized if
reservoir cap it says 21 psi and if you take a look right here on this radiator cap it says 16 psi and when you pressurize liquids the boiling point increases so at 15 psi water boils at 250 degrees fahrenheit
and coolant boils at 260. so making sure your antifreeze prevent it from boiling over like that now the second thing coolant here we have the water pump from my pickup
truck before i owned it the owner used straight water in the cooling and that scale in the water pump and the radiator was 20 times worse and what happens is when you have scale and rust clogging up the radiator it
cooling system is just working harder to keep that engine at operating it could also cause things to fail such as the water pump which is why i had to now antifreeze has additives in it that prevents corrosion check out this bolt
condition and then if we check out this bolt you can see it's all rusted water does not have any of those additives in it finally if you take a look at this water pump that was in my jag
compared to the one that was in my truck and that's because before the jag got a head gasket leak it was running fresh 5050 coolant and then the last major thing that coolant does is it prevents your cooling system from
freezing water freezes at 32 degrees fahrenheit and 50 50 coolant freezes at negative 34 degrees fahrenheit and it's important that water does not freeze could actually break the engine it could crack the block
when it freezes you can see this used to be at the same higher because this is frozen you might have experienced this when you in the freezer and it expands and breaks that soda can
and as you guys know i don't like to just tell you things i like to show you so what we're going to do is we're going to fill this pipe up with antifreeze a and we're going to fill this pipe up with regular plain old water h2o
going to leave them out overnight in the below freezing weather and just wait and see what happens it's amazing so let's fill the antifreeze metal pipe with 50 antifreeze and 50 water good
water pipe with well just water good all right so now we have our 50 50 antifreeze pipe and our 100 water pipe and let's let these sit outside in the freezing cold overnight and also i thought it'd be
plastic as well so let's add a 50 50 mix antifreeze water into one pipe and our plain water into the other pipe outside overnight as well in the freezing cold and let's see
what happens this should be good alright so a couple of freezing days later tests because look at this so the cap here actually blew off it from the expanding ice the ice had nowhere to go in here so it had to go
how strong it is and if we take a look at the pvc pipe anything apart because pvc has a little bit more flexibility but you can see that nice big crack just picture the plastics in
leak out all the coolant and then meanwhile the 50 50 ratio protected there is no damage at all it's not blown apart you can see there's no cracking or so that's why you run a 50 50 ratio now one last thing i want to mention is
gonna get comments on this so this right here is an extra engine i have so we could supercharge the drift car and if we take a look on the side these right here are freeze plugs this is what they look like they are a press
they got this name because people running straight water or not enough antifreeze in the winter would come to their car with these on push them out now this could actually save your engine
block from cracking it won't work all the time but that's how it got this name actually are are just plugs for the block for when they cast it this is how make sure you get all that sand out when the blocks are actually made at the
foundry so that's how a freeze plug got its name it's not designed to prevent don't rely on this instead make sure you have that 50 50 mix so that you don't have any chance of the block freezing
important to have that 50 50 ratio of antifreeze to water in your cooling so it runs properly now let me show you how to test it here are all the tools and products you need and as usual we're using common hand tools
can do this exact same thing at home yourself no problem at all one of these antifreeze testers also known as an antifreeze hydrometer simple to use and inexpensive this is only five bucks i'll be sure to link
the next thing you might need is a funnel you can use any funnel i really recommend one of these spill proof funnels they work amazing for the especially if you have air in your cooling system maybe you don't have a
that could signify that there is air trapped in the heater core and if so i will show you how to get all that air out in this video that way you have nice description as well
and then finally we need to get some good old antifreeze we're using peak 10x it works in any make and model and you can mix it with which is perfect because we're going to be topping off the antifreeze we're not
our tester says we might need to add straight antifreeze we might need to add just 50 50 and top it off or we might need to add distilled water now when adding water to your cooling system it has to be pure
this if you add tap water if you add water from your hose bottled water any of that stuff that has minerals in it so make sure you find distilled water and doesn't have anything that says minerals added for example
this water right here you can see it says enhanced with minerals for taste although it is purified water it's not distilled and it has minerals in it so i wanted to cover that real quick because i see people add hose water or
all the time and you don't want minerals in there minerals will coat the inside and make it so that there's less heat transfer also it'll increase the rate of you use that distilled water and with that that's all the tools and
very much for supporting the video and sending me out the coolant that way i how to properly test your coolant and then top it off with the correct ratio so with that said let's go get started let me show you how to test the coolant
so the first car we're gonna test is susan the previously vandalized car that summer i have no clue the condition of the coolant system so that's the perfect especially before the winter now what we're going to need to do is get a
to fill this up so you need to find access to the coolant and in this case right here that we could get our sample from now whenever you're working on the super super important before you do anything make sure the coolant cap is
cool to the touch it cannot be hot these systems are pressurized when it's pressurized you'll get hot scalding coolant pouring all over you which would not be fun so this cap is cool which means we could remove it then we
could grab our antifreeze tester and insert the hose into the coolant reservoir to press the bulb and it's very important we get enough coolant to fill all the way up to our fill line right here you can see right
fluid level we need it to that level or higher and once we have our sample we could remove it from the reservoir and let's so the way you read this on the side here is your freezing point in blue we
in red we have celsius this is the temperature at which your coolant will freeze at a perfect 50 50 ratio we have negative 34 degrees that's the freezing point so we have negative 35 right there close enough these things aren't crazy
so we just want to make sure our arrow here points in this vicinity now before there's two things you want to do one you want to make sure you tap on it like that's very important because there could be bubbles supporting this float
bubbles could be supporting it up and giving you a false reading and two if we take this and we tilt it to the side you can see the arrow is no longer we want the arrow to be in the crosshair which means that our reading is level
otherwise our float moves side to side so line up that arrow in the crosshair and make sure there are no bubbles which there aren't and then take a reading you can see it's right around negative 34 degrees
perfect we have a 50 50 ratio of antifreeze to coolant that is what you want to see now while this tool is very helpful you did hear very accurate i mean it's only five bucks but there is a good way to test it
relatively accurate and that is get a cup of distilled water distilled water because we know distilled water's freezing point is 32 degrees fahrenheit zero degrees celsius so we have a freezing point
that we know for sure and with just plain water our freezing point is right that freezing point and it's a little bit below so like i said it's not 100 accurate but it's pretty close so that gives you
it for have 50 50 in here we could put our cap back on and make sure you tighten it down all the way just like that beautiful
look at real quick is to make sure our coolant level is look at the side of the cooling system you can see it says minimum and maximum and then our coolant is right above that maximum line
line i definitely recommend filling it up to the maximum line difference in the cooling capacity of your system we are a little bit above which isn't a big deal if it was way
consider taking some out so you have room for expansion but being a little bit above isn't a big deal but always check this checking your coolant so you know it's at that optimal 50 50 ratio it
takes less than a minute to do it's less than five dollars to buy one to check it and it could save you thousands of engine block goes bad from overheating or from cracking in the winter
to check it's a little bit different it is your with straight water in the summer or you buy washer fluid in the summer from the they're probably using a summer mix which doesn't protect as cold
so you need to definitely make sure that you change this out and what we're going is washer fluid that not only has de-icer in it which will help when the but it's good to negative 25 so we don't
also potentially the lines freezing and freezing and cracking all bad things that we don't want so in order to get all this out of here go in the car and hit the wipers holding
we'll remove enough washer fluid so that you could add your winter washer fluid pretty much empty or at least close to it we could fill it up with our winter washer fluid and this will give us the protection we need for freezing and also
off the windshield good and the last thing to do is hit of seconds to flush the new fluid they don't freeze beautiful so our coolant's good
to worry about anything freezing over the winter and we are done all right so now you know how to test your coolant but what happens if your coolant isn't at that ideal 50 50 ratio probably like what we're gonna find in
the jag the jag had a head gasket leak or maybe it still has one i don't know i'm making another video all about using a head gasket sealer documenting it showing you guys how i added it and whether or not it works and
so it's going to be over a year giving the meantime what that means is we added a lot of water to the system because the engine was consuming a lot of coolant and it got expensive constantly
we topped it off with straight water definitely not the best thing to do but this so let's go check out this coolant again cool which it is and for whatever reason the caps on these jaguars are a
pain to remove there we go and now we can take our sample definitely mostly water so if you take a look good thing we're to 10 degrees fahrenheit about negative 12 celsius which it
sometimes where i live so that could have been bad now let me show you what we need to do to get this ratio 50 50. first we need to make
want and remember to chalk off the rear wheels so with the car safely lifted up and drain the radiator so we can get the correct ratio so let's go get our safety and i have my drain pan ready and let me go show you where the drain plug is
way is facing forward you're going to look behind the grill for the radiator that's this silver piece right here and you want to go to one of the corners will have the drain valve in this case
so that is what we're going to have to unscrew to drain the radiator i'm using a flathead screwdriver and be very careful because this valve is just so unscrew it and you can see the coolant starting to come out so continue
the way and there you go definitely have that drain pan under there aimed properly because this coolant is coming out quick and now we just have to wait until it completely drains and once it's drained
and make sure you tighten this but don't go crazy you want it to be snug but don't force it again this is just plastic all drained of coolant that doesn't mean we drain the entire cooling system there's
the heater core and probably some of the hoses but we did drain it enough that way when we add our new coolant we could get our 50 50 figure out how much antifreeze we need to add we need to figure out how much we
old bottles of antifreeze like this you know they're a gallon each and just fill luckily i have one of these large fluid storage containers which has the volume easy for me to bring all this coolant to the parts store to
be recycled when we're done so the entire cooling system in the jag is just about eight quarts or two gallons so with about a gallon removed or four quarts now let's figure out how much we need to add to get to that
the first thing you need to do is check the total capacity of your cooling in your owner's manual so in the jag the total capacity is eight quarts now just down to 10 degrees fahrenheit so if we
here you can see 10 degrees fahrenheit that gives us an antifreeze concentration of 25 percent and water concentration of 75 percent so removed four that gives us four left in the system and then to
water there is the four quarts left in the system times one quart of antifreeze and then the four quarts left in the system times 75 water so what we want to do is we want to get
this ratio to 50 50. this is what's still left in the car simple we just need to add two quarts of antifreeze straight water 50 50. and then from there we could just
50. and don't worry i'll be sure to link easily find it that way you could reference the temperature and your antifreeze and water concentration so let's go fill our cooling system so now
our two quarts of straight antifreeze this is that spill proof funnel i was these are the adapters we need for the jag that goes in there like that and then this just tightens down and then finally our funnel connects
just like that so now we need to add two quarts of full strength antifreeze this has to be concentrated antifreeze that way we could get that 50 50 ratio has 10 times the concentration of corrosion inhibitors in it which is
system from corroding so let's finish up pouring those two quarts into the good and now we can top this off the rest of the way with our 50 50 antifreeze knowing that our ratio inside the cooling system is 50 50.
up then let's start the car and back off on level ground that way the bubbles in the cooling system aren't trapped and now with the car level we're going to let it run until it warms up
all the air bubbles will start to flow out we do want to go and you want to turn your heat on all the way that way if there is a heater control valve it will open up so now the coolant is
flowing through the heater core and our air will be nice and toasty once all those bubbles are pushed out and as the car runs you can see the trapped air coming out of the system and those bubbles are being replaced by
and after about 10 to 15 minutes of the engine idling our thermostat has opened up because we're at operating temperature and if we take a look here you want to make sure you keep this topped off but i'm not going to because
we're going to need our system has been completely bled of well is because if you take a look the heater core the engine the radiator they are all way lower than the highest
so now we can shut the car off we could get our plunger and plug the funnel that the coolant pouring out and then let's remove the adapters from the reservoir and finally let's take a sample to make
sure we have that 50 50 ratio and check it out we are at that negative a 50 50 ratio in our cooling system beautiful now one last thing we need to do don't
forget the top off the washer fluid with the winter mix that way it doesn't this cat mice were actually chewing away at this i found a little nest keep warm but we'll get that back on there and that'll do for now
checking your coolant and making sure it's that perfect 50 50 ratio so your engine and cooling system is protected was remember to give it a thumbs up if you're not a subscriber consider hitting
and as always all the tools and products i used in this video i used in this video are linked in the description