Coolant change or flush?
Thread Starter
Burning Brakes
Joined: May 2018
Posts: 885
Likes: 270
From: New Castle, IN
C6 of Year Finalist (stock) 2019
Coolant change or flush?
I know I've seen a few post on here about this....My '11 GS has 12K miles, I purchased it last April with 9300 miles and I'm positive it has the original coolant, should I flush the system, or let it drain and refill with a 50/50 mix of Dexcool?
Team Owner
Joined: May 2000
Posts: 53,833
Likes: 5,641
From: Plantation Florida USAF(Retired) 1966-1990
U.S. Air Force
St. Jude Donor '05 thru '26
NCM Sinkhole Donor
The cost is little, and you no it's done properly serviced.
MY motto, is if you can afford a Corvette, why are you putting in regular gas to save a buck, and why not have coolant changed properly.
Burning Brakes
Joined: Feb 2007
Posts: 904
Likes: 133
From: Kerrville, Texas
I have a 2012 and will drain and refill mine the first nice day that comes along but I really don't think it's necessary. It has the original coolant in it. I'll also use distilled water.
Drifting
Joined: Jul 2011
Posts: 1,519
Likes: 235
From: Pa
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Race Director
Joined: Apr 2007
Posts: 16,025
Likes: 1,656
From: Toronto, Canada
C7 of the Year - Unmodified Finalist 2021
Race Director
Joined: Oct 2005
Posts: 14,555
Likes: 1,255
From: Saint Albans, WV
I'm with you on potable water but potable water is defined as any safe to drink. Distilled water is potable but most people would not like the taste but it is still potable. I know for a fact dealers use tap water so the distilled water to me is unnecessary.
Thread Starter
Burning Brakes
Joined: May 2018
Posts: 885
Likes: 270
From: New Castle, IN
C6 of Year Finalist (stock) 2019
So use straight coolant a potable water vs 50/50 mix?
Racer
Joined: Sep 2019
Posts: 488
Likes: 206
From: Indy `O=o-
2020 C6 of the Year Finalist - Unmodified
I like to use distilled or at least soft water. You won't get crusty calcium buildup in places the cooling system might seep (host connections, water pump housing, internal cooling passages, etc) and it is ph neutral so it won't attack the aluminum block.
Mine is original too from 2012. I think its about 129 for flush and fill at dealer?
Race Director
Joined: Jul 2005
Posts: 12,056
Likes: 3,588
From: Central MO
I've always used tap water, as the antifreeze manufacturers typically say it's OK. Open the petcock, drain the radiator. Close the petcock, fill through the overflow tank with water, start car and top off as the overflow tank goes empty. Let the coolant circulate for a while after the thermostat opens up. Shut the car off and drain the radiator again. Fill again, repeat the run time. This time when you drain the radiator it should be pretty much just water. Close the petcock and refill the system with 100% Dexcool - the block is full of water only and contains pretty close to 50% of the system fluid capacity. So by filling the radiator with Dexcool you end up pretty close to a 50/50 mix. That's the way I have always done it and never had a cooling system issue. I have owned several vehicles for as long as 14 years. I have always changed based on the OEM or coolant manufacturer's recommended timeline; I believe that is 5 years for Dexcool. It's 10 years for my F-150 and the wife's Charger.
Last edited by BadAV; Jan 15, 2020 at 08:17 PM.
Race Director
Joined: Oct 2005
Posts: 14,555
Likes: 1,255
From: Saint Albans, WV
Le Mans Master
Joined: Oct 2000
Posts: 6,509
Likes: 724
From: Sausalito CA
But the OP question concerning the 5 year Dexcool life.....
Drain and refill or Flush
My Vote: Flush as I understand Dexcool can "gum up" with age.
Yet drain and refill is a whole lot easier if DIYing.
Drain and refill or Flush
My Vote: Flush as I understand Dexcool can "gum up" with age.
Yet drain and refill is a whole lot easier if DIYing.
Burning Brakes
Joined: Jan 2017
Posts: 824
Likes: 369
From: Fort Worth Texas
Finalist 2021 C3 of the Year - Modified
C3 of Year Finalist (appearance mods) 2019
C6 of Year Finalist (stock) 2019
2018 C6 of Year Finalist
Safety Car
Joined: Aug 2017
Posts: 4,931
Likes: 2,340
From: Etobicoke (Toronto) Ontario
From the DeWitts FAQs "Aluminum is very sensitive to minerals and chemicals in all sources of water, and only distilled water should be used" to mix with the coolant. They go on to say either that, or use the premixed stuff. So, when the DeWitts rad was put in, the coolant system was flushed to purge all of the old coolant, including the heater core, and distilled water was used as recommended. I'd be avoiding tap water, since most of it is chlorinated. There are additives to Dexcool which fight corrosion but in doing so, they get used up. Hence the need to change it at the 5 year mark. Even if you don't have a DeWitts rad, all the OEM roads have aluminum cores. Some have aluminum end tanks.