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red and green antifreeze...can they be mixed?

I just bought a 2001 Suburban with 5.3 engine. It came with green antifreeze, but the DEXCOOL I bought is red. Can they be mixed? Can I use the red to top off the green?


  • edited April 2009
    No, they can't be mixed under any circumstances. It will turn into acid and eat away your head gasket.

    If I were you, I would return the Dex Cool, use the green stuff, and drain and refill every two years.
  • edited April 2009
    Whitey, I will keep an open mind but I would like to be directed to the source of your information about the two products turning into some type of acid when mixed.Surely there must be info out there about this. I wiil determine if the info is credible.

    If I were you OP I would never even walk down the isle in the parts store that DexCool is displayed.
  • edited April 2009
    Both antifreezes are ethylene glychol. The only differences between them is the additive packages. So they can be mixed, only in doing so you must treat the cooling system as if it has the regular green coolant in it.

    Dexcool alone will turn acidic if the cooling system gets air trapped in it. So to avoid that problem, return the Dexcool and keep using the regular green antifreeze.

  • edited April 2009
    Whitey is right, they cannot be mixed.

    Not all coolant mix is the same. Some use a component that causes a protective oxide layer to form on the insides of the parts, much like the copper oxide layer on the Statue of Liberty protects it from deterioration. Others use a silicate coating to protect the insides of your parts. Other additives may vary also. The determinant is what the insides of the engine is made of as well as the manufacturer's design philosophy. You do not wnat to mix these, nor do you want to use the wrong one.

    There is no reason to use anything other than what the manufacturer recommends for any fluid, and with some the risk can be great. Coolant additive is one of these.
  • edited April 2009
    Maybe "acid" wasn't the best choice of words, but when you mix additive packages and rust inhibitors, you never know how they are going to react. After all, Dexcool is made with "organic acid technology." ( Also, "the OAT (organic acid technology) will cause precipitation of silicates in the green type and corrosion protection is greatly reduced." ( So this probably won't make your coolant "turn into acid," but it will make your coolant more acidic than it was.

    "If the coolants become mixed with Dexcool?, however, one study showed a possible aluminum corrosion problem in certain situations." (

    According to GM, "Mixing a ?green? coolant with DEX-COOL reduces the batch?s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed." (

    I don't believe it. I have seen too many stories about head gasket problems that only manifested themselves after the coolants were mixed. I also find instances where GM warns not to mix Dexcool with other coolants:

    "On its website, the company now also warns owners to consult their vehicle 'owner's manual for the type of coolant right for your vehicle' and never 'mix one type of coolant with the other.'" (
  • edited April 2009
    I'd return the red Dexcool and exchange for the universal coolant. Talk to the salesperson: This product can be used in Dexcool and green coolant applications.
  • edited April 2009
    I had the coolant changed on my wife's Nissan. The shop put in DEXCOOL, without my knowledge; later I topped it off with a normal antifreeze, and wrecked a 1 year old Nissan radiator!!!

    Sooooo; I would steer away from DEXCOOL under ANY circumstances, never mix it with anything else, and use the regular green stuff, and change every 2 two years!

    GM is the only one who really doesn't know how bad this stuff is, or they are not admitting it!
  • edited April 2009
    Some urban legends just won't die!

  • edited April 2009
    Which urban legend would that be? The urban legend that you can mix Dexcool with other coolants is definitely false. Even GM says so on its web site.

    "Never mix one type of coolant with the other." <
    cited from
  • edited April 2009
    Read what Texaco, who makes Dex-Cool says about mixing the two.

This discussion has been closed.