Coolant question
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 876
Likes: 23
From: Prescott Valley, AZ
Coolant question
according to the manual, coolant should be a 40/60 mix of dexcool and water. i know dexcool comes in 100% and 50/50 mix containers. can the 50/50 mix be used or must it be a 40/60 mix? trying to get that right will be problematic. especially when just adding some from time to time.
Safety Car
Joined: Dec 2012
Posts: 3,812
Likes: 1,839
From: St. Louis Metro East IL
Yes, you can use 50/50 which gives a lower freeze point. I don't know of any reason to use 40% antifreeze / 60% water except for cost. Maybe someone will educate me.
From the manual section on coolant (not just the recommended fluids table):
If ambient temperatures are
anticipated below −28°C (−18°F),
make sure a proper mixture ratio of
50% DEX-COOL coolant and 50%
clean, drinkable water is used.
Ron
From the manual section on coolant (not just the recommended fluids table):
If ambient temperatures are
anticipated below −28°C (−18°F),
make sure a proper mixture ratio of
50% DEX-COOL coolant and 50%
clean, drinkable water is used.
Ron
Last edited by RonC7; Nov 14, 2017 at 06:35 PM. Reason: .
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 876
Likes: 23
From: Prescott Valley, AZ
Yes, you can use 50/50 which gives a lower freeze point. I don't know of any reason to use 40% antifreeze / 60% water except for cost. Maybe someone will educate me.
From the manual section on coolant (not just the recommended fluids table):
If ambient temperatures are
anticipated below −28°C (−18°F),
make sure a proper mixture ratio of
50% DEX-COOL coolant and 50%
clean, drinkable water is used.
Ron
From the manual section on coolant (not just the recommended fluids table):
If ambient temperatures are
anticipated below −28°C (−18°F),
make sure a proper mixture ratio of
50% DEX-COOL coolant and 50%
clean, drinkable water is used.
Ron
I'm Batman..
Joined: Apr 2014
Posts: 6,142
Likes: 920
From: Lehigh Acres FL
Tech Contributor
Yes, you can use 50/50 which gives a lower freeze point. I don't know of any reason to use 40% antifreeze / 60% water except for cost. Maybe someone will educate me.
From the manual section on coolant (not just the recommended fluids table):
If ambient temperatures are
anticipated below −28°C (−18°F),
make sure a proper mixture ratio of
50% DEX-COOL coolant and 50%
clean, drinkable water is used.
Ron
From the manual section on coolant (not just the recommended fluids table):
If ambient temperatures are
anticipated below −28°C (−18°F),
make sure a proper mixture ratio of
50% DEX-COOL coolant and 50%
clean, drinkable water is used.
Ron
Racer
Joined: Sep 2004
Posts: 257
Likes: 0
From: Overland Park Kansas
I agree the higher percentage of water the better heat dissipation. I don't know how much better or if you would ever notice the difference but water does dissipate heat better than antifreeze.
Race Director
Joined: Jan 2014
Posts: 10,709
Likes: 7,098
From: Fulshear, TX
The C7 cooling system holds 11.3 quarts which is 2.8 gallons. 1 gallon of straight DexCool then 1.8 gallons of pure water will get you to a 36/64 blend which is pretty darn close to what you need. Assuming you will never get the system perfectly drained I would be willing to bet 1 gallon of straight DexCool plus topping off the remainder with water will get you where you want to be. This is going to be the most cost-effective way of doing it, but you could also do 2 gallons of 50/50 then fill the remainder of space with straight water. I would then personally add a bottle of Redline Water Wetter to whatever mix you do.
Last edited by Kracka; Nov 15, 2017 at 09:03 AM.
Tech Contributor
Joined: Oct 1999
Posts: 40,995
Likes: 9,759
From: Charlotte, NC (formerly Endicott, NY)
Simple enough to get a 60/40 mix of water to dex for top offs if needed. Get a large container and add 2 quarts of Dex followed by 3 quarts of water. Don't bother buying the 50/50 mix as they are charging a higher price for selling you less coolant.
However, if your coolant level is dropping you may need to do more than top it off. You could have a leak somewhere. I see very little drop off in coolant level in any of my cars including my 03 Tahoe with 113K miles. It takes a long time for the water to evaporate out of the system. If the level is dropping due to evaporation then the concentration of coolant will increase and the proper top off is just to add enough clean drinking water to bring it back up to level.
Bill
However, if your coolant level is dropping you may need to do more than top it off. You could have a leak somewhere. I see very little drop off in coolant level in any of my cars including my 03 Tahoe with 113K miles. It takes a long time for the water to evaporate out of the system. If the level is dropping due to evaporation then the concentration of coolant will increase and the proper top off is just to add enough clean drinking water to bring it back up to level.
Bill
Racer
Joined: Sep 2017
Posts: 359
Likes: 88
From: Alaska
I remember reading several engine swapping guides that recommended a 40/60 blend as making the difference between overheating and not in a cooling challenged application (even some of the 4.3L S10s IIRC).
Not hard to see GM's point of view, if they don't recommend driving the car below +40°F because of the tires, it makes sense to me they would bias the cooling system to prevent overheating more than freeze prevention.
Not hard to see GM's point of view, if they don't recommend driving the car below +40°F because of the tires, it makes sense to me they would bias the cooling system to prevent overheating more than freeze prevention.
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Le Mans Master
Joined: Sep 2003
Posts: 8,847
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From: Longview Texas
Even if you drain the system, I never attempt to add pure antifreeze and then hope I can get enough water in to get the right mix..
I just keep and extra jug with the correct mix, and then add whatever amount is needed to fill the system. I have been keeping 50/50 mix, but could just as easily keep 40/60 mix.
I just keep and extra jug with the correct mix, and then add whatever amount is needed to fill the system. I have been keeping 50/50 mix, but could just as easily keep 40/60 mix.
Racer
Joined: Sep 2017
Posts: 359
Likes: 88
From: Alaska
I'm Batman..
Joined: Apr 2014
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From: Lehigh Acres FL
Tech Contributor
Racer
Joined: Sep 2017
Posts: 359
Likes: 88
From: Alaska
I'm Batman..
Joined: Apr 2014
Posts: 6,142
Likes: 920
From: Lehigh Acres FL
Tech Contributor
Tech Contributor
Joined: Oct 1999
Posts: 40,995
Likes: 9,759
From: Charlotte, NC (formerly Endicott, NY)
Even if you drain the system, I never attempt to add pure antifreeze and then hope I can get enough water in to get the right mix..
I just keep and extra jug with the correct mix, and then add whatever amount is needed to fill the system. I have been keeping 50/50 mix, but could just as easily keep 40/60 mix.
I just keep and extra jug with the correct mix, and then add whatever amount is needed to fill the system. I have been keeping 50/50 mix, but could just as easily keep 40/60 mix.
Bill
