Coolant replacement?

Tiny
SIRJR
  • MEMBER
  • 2018 CHEVROLET EQUINOX
  • 1.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 37,000 MILES
You've helped me with the coolant change on my Cruze/Sonic/ATS and now I need help/information with the procedure on our vehicle listed above. I do not know how similar/different it is to do on the vehicle listed above. Thank you.
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Friday, July 24th, 2020 AT 5:34 AM

6 Replies

Tiny
DANNY L
  • EXPERT
Hello, I'm Danny.

Your vehicle does not require a coolant change until 150,000 miles per routine maintenance. The DEXCOOL brand coolant can last that long unless there are any leaks in the system. Hope this helps and thanks for using 2CarPros.
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Friday, July 24th, 2020 AT 6:12 AM
Tiny
SIRJR
  • MEMBER
I know the recommended GM DexCool maintenance is that interval; however, due to the history of that product, I always change it on my GM vehicles sooner to prevent issues that could develop over time. Also, being in Florida, I like to change the coolant sooner than the manufacturers time frame. This is why I was asking for the information on changing the coolant in our Equinox.
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Friday, July 24th, 2020 AT 11:28 AM
Tiny
CARADIODOC
  • EXPERT
Hi guys. You're right to replace it sooner. This was one of GM's many tricks related to their "customer-unfriendly" business practices. They aren't the only manufacturer that does this, but it ends up costing car owners in the long run.

Antifreeze is alcohol, and it's going to be alcohol no matter how long it stays in the system. It's the additives that wear out in about two years. Those include corrosion inhibitors, water pump lubricant, seal conditioners, and anti-foaming agents. It's those additives that wear out in about two years and is why we replace the coolant that often.

When GM first started using Dex-Cool, they advertised it as "lifetime" antifreeze, but then on the reservoir they put a sticker that says to replace it every three years. Even the Dex-Cool company doesn't recommend that. They specify every two years, the same as all other brands. Ford did that with their 7,500 mile oil change recommendation. It's done to make their cost of regular maintenance look less expensive than that of their competitors, which could tip the scale when deciding which new car to buy. If you followed the owner's manual, it was almost impossible for anyone to fall under the "normal" service. If you drove excessively in the city, mainly at highway speed, on dirt roads, or any of a half dozen other conditions, you fell under the "severe" duty chart and were back to the normal 3,000-mile interval, but legally they could still advertise the 7.500-mile interval.

A lot of mechanics like to flush the cooling systems on GM vehicles, then use a different brand of coolant. (We call Dex-Cool, Dex-Mud", because that is what it can turn into if mixed with other brands, or when it gets old. That's an argument I prefer to stay out of. While it might not be the best brand, it does meet GM's requirements for the metal alloys in their engines. My personal opinion is you run into trouble when you treat it like the marketing executives advertised.

What you might consider is performing a simple test to see if there is excessive acids built up in the system. Those acids form in all cooling systems from combustion gases sneaking into the coolant. The corrosion inhibitors neutralize that acid, but as I mentioned, they wear out in about two years. After that, any time you have an acid and two different types of metal, you get "galvanic action", similar to how a car battery uses acid to develop its current, and that means corrosion. This leads to leaking heater cores and radiators. It is not uncommon to run into that on 20 - 40-year-old cars, but for the last 20 years or so, it has been real common to find that on GM vehicles less than five years old.

There's aluminum, copper, iron, and brass in most cooling systems. There's your two different kinds of metal. Once you have depleted corrosion inhibitors, you get that corrosion in the heater core and radiator. To check for that, use an inexpensive digital voltmeter with the negative probe on the battery's negative post, (or an unpainted point on the engine), then dip the positive probe into the coolant. On all other car brands you must be careful to not stick the probe into the radiator so far that it touches metal. Most GM radiators don't have radiator caps any more so you have to go to the reservoir. The test is done the same way, but you don't have to worry about touching metal. You'll usually need to switch the meter to the 20-volt scale. Any reading under 2.0 volts is considered acceptable and normal. With old Dex-Cool, it is common to find up to 12 volts, but anything over 2.0 volts is considered to have excessive acid build-up in the coolant.

I'll go back to my corner now and let you guys figure out the best course of action. Will watch to see what works for you so I can add it to my memory banks.
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Friday, July 24th, 2020 AT 7:52 PM
Tiny
SIRJR
  • MEMBER
Please explain to me the correct procedure to change the coolant in my vehicle. Thank you!
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Saturday, July 25th, 2020 AT 12:17 PM
Tiny
CARADIODOC
  • EXPERT
Until Danny L replies, I'll share my procedure at the dealership. Most cars got a general flush and fill. A lot of shops use a special flushing machine that forces water through the system in various directions to dislodge debris. At the first service, there's bound to be casting sand stuck in there that never got fully shaken out at the factory. Some of that sand may have collected in the heater core. One disadvantage to this method is the flushed-out water goes down the drain and could be an environmental issue.

My procedure was to drain the old coolant into a drain pan that gets emptied out into a tank for recycling. By the way, since the mid '90s, most radiator tanks are made of plastic, and have plastic petcocks. I strongly recommend to never use that. Pull the lower radiator hose off instead. We had a rash of radiators that had the plastic crack inside the tank where the rubber o-ring seals up to, then there would be a constant drip about once every five seconds. The only fix for that was to replace the radiator.

With the coolant drained, I remove one heater hose at the engine, not at the heater core. GM uses a lot of heater cores with plastic tubes. I worry about breaking one of those tubes by twisting and tugging on the hose. At this point I drive the car to the garden hose and use that to push water into the heater hose, then the heater core, then the radiator, then finally I overfill the reservoir, pull its hose off the radiator and let it hang so the water will siphon itself out. A pressure washer works well to clean the inside of the reservoir.

When you buy your new antifreeze, do not fall for that "pre-mixed" 50 percent water. That might be fine for a newly-rebuilt engine, but after any flushing procedure, there is going to a lot of clean water left in the engine block that never drains out. If you add that 50 / 50 mix, you'll always have less than 50 percent antifreeze. Instead, for a four-cylinder engine, I started by adding one full gallon of new antifreeze, then I alternated a half gallon of water, then a half gallon of antifreeze, until the system was full. Run the engine long enough for the thermostat to open so the coolant mixes thoroughly, then test the freeze point. You can adjust the freeze point by adding up to a half gallon of water or antifreeze to the reservoir.

Four-cylinder engines in particular often have a thermostat housing design where air remains trapped until it is manually bled out. If you don't do that, the engine will overheat. Thermostats have to be hit with hot liquid to open; hot air won't do it. Many engines have bleeder screws on the thermostat housing for this purpose. If there is none, look for a coolant temperature sensor that can be unscrewed momentarily. Older Chrysler engines also had a threaded plug that could be removed. You don't have to run the engine during this bleeding procedure. Just remove the plug, then fill the system until coolant runs out that hole.

If you do remove a temperature sensor, and you have to unplug it, do that with the ignition switch off. If the switch is on, the Engine Computer will detect the break in the circuit and set a diagnostic fault code that if not erased, could confuse a mechanic in the near future.

Checking the freeze point is a lot more complicated than would seem. Almost all of the testers you can buy calculate the freeze point by comparing the weight of the coolant to the weight of straight water. As you add more and more antifreeze, which is heavier than water, the number of floating balls will increase, or the pointer will go higher on the scale. The issue here is the indicator will falsely indicate a really high freeze point in straight antifreeze, in the order of minus 70 degrees. In reality, the old green antifreeze turns to slush by around minus ten degrees, and water freezes at 32 degrees. It's when the two are mixed that the freeze point becomes lower, but minus 50 degrees is about the lowest it can achieve. To say that a different way, once you pass roughly 60 - 70 percent antifreeze, the common testers will falsely indicate the freeze point is getting lower and lower, but the actual freeze point will turn around and start to go back up toward minus ten degrees. All antifreeze manufacturers recommend a 50 / 50 mix to get the best freeze protection.

Also be aware antifreeze holds relatively little heat so it does a poor job of moving heat from the engine to the radiator. Water is very effective at absorbing and moving heat, so you need a sufficient percentage of water in the system. Antifreeze is good, but more is not better.

If you want to truly know the exact freeze point, you need a tool called a "refractometer". There is a sight glass hat has to be perfectly clean. Dirt adversely affects its accuracy. You place one drop of coolant on the sight glass, close a cover over it, then you sight through the tool. What you see in the window will be light on top and darker on the bottom. At that transition is where you read the freeze point on the scale on the side. Even most professionals don't have or use that tool. As long as you're reasonably close to a 50 / 50 mixture, the inexpensive testers with pointers and floating balls will be within their range where they're pretty accurate.
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Saturday, July 25th, 2020 AT 2:09 PM
Tiny
DANNY L
  • EXPERT
Hello again.

I must admit after owning quite a few GM vehicles with DEXCOOL I'm not a fan of it either. The first thing I did was flush the system and eliminate DEXCOOL all together and replace with regular Polypropylene Glycol. All cooling systems are sealed and pressurized but the main problem is when it comes in contact with air it starts to thicken and clot up. Here is a basic cooling system flush tutorial for you to look at:

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

I have attached picture step-by-step instructions below to help for your car. Hope this helps and thanks again for using 2CarPros.

Danny-
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Saturday, July 25th, 2020 AT 3:22 PM

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