Antifreeze and Coolant Types Explained: IAT, OAT, HOAT and ELC
October 16, 2026 · RPS Distributors
Coolant does more than stop your engine from freezing. It prevents overheating in summer and protects the radiator, water pump and engine block from corrosion all year. Using the wrong type — or mixing types — can cause gelling, sludge and expensive cooling system repairs.
The main coolant types
| Type | Full name | Typical use | General service life |
|---|---|---|---|
| IAT | Inorganic Additive Technology | Older cars and trucks (mostly pre-2000s) | Shorter — often around 2 years |
| OAT | Organic Acid Technology | Many newer cars and light trucks | Long life — often around 5 years |
| HOAT | Hybrid Organic Acid Technology | Many European, Ford and Chrysler vehicles | Long life |
| ELC | Extended Life Coolant (heavy duty) | Class 8 trucks and diesel equipment | Extended — check the engine maker's spec |
Always follow the vehicle or engine manufacturer's recommendation and the service interval on the label.
Do not choose by color
Green, orange, yellow, pink and blue coolants are common, but color is just dye. Two coolants of the same color can have different chemistry. Read the label and match the specification, not the color.
Can you mix coolant types?
It is best not to. Mixing different chemistries can reduce corrosion protection and, in some cases, cause sludge. If you do not know what is in a system, flush it and refill with the correct type. "Universal" or "all makes, all models" coolants are designed to be compatible with most systems and are a safe choice for top-offs.
Concentrate or 50/50?
- Concentrate must be mixed with water (ideally distilled) before use. It is cheaper per gallon of protection.
- 50/50 prediluted is ready to pour, which saves time in shops and at gas stations.
- A 50/50 mix of standard ethylene glycol coolant typically protects to around -34°F.
Test freeze protection before winter with test strips or a refractometer.
Antifreeze brands we carry
RPS Distributors stocks Peak, Shellzone, Pride, All Season and OEM coolants in concentrate and 50/50, plus heavy duty options for fleets. Browse the Antifreeze & Coolants collection and stock up before the first freeze.
Shops, dealers and gas stations — request a wholesale quote or call 1-855-498-7509 for case and pallet pricing.