98.002: Nitrited Organic Acid (NOAT) and Organic Acid (Dexcool) Compatibility


Many customers have expressed a desire to use various brands of OAT and/or NOAT antifreezes or coolants. These coolants are sometimes referred to in the field as “Long Life” coolants. The term was found to be trademarked, and should not be used. OAT and NOAT coolants also have been shown to have service life inferior to modern inorganic extended service interval (ESI) coolants.

Penray’s Recommendation:

Various brands of OAT and NOAT coolants have been reviewed. The following are known to be compatible with each other and may be mixed without affecting the fluid’s performance.

  • OAT (Orange) type coolants: GM® Dexcool®, Texaco® Havoline®, all brands made with Penray 2798 inhibitor technology, Prestone® Extended Life.
  • NOAT (Red-orange) type coolants: Caterpillar® Extended Life, Texaco® Extended Life, all brands made with Penray 2798N inhibitor technology, Detroit Diesel® PowerCool® Plus.


Do not mix other coolants with the above types of coolants. Serious problems may result. Never mix green, blue, purple or pink coolants with the orange and red-orange coolants without converting the OAT/NOAT coolant to inorganic inhibitors. It is now possible to convert OAT/NOAT coolants to a Penray Fill-For-Life® program. See Technical bulletin 01.008.

If the coolants become mixed, drain, clean and flush the cooling system. Refill it with a quality, fully formulated coolant