Coolant & Antifreeze: What You Need to Know

Not all antifreeze is the same — using the wrong type can damage your cooling system. Here's what you need.

Engine coolant (antifreeze) does far more than prevent freezing. It raises the boiling point of the coolant, lubricates the water pump seal, prevents corrosion inside the cooling system, and contains additives that protect aluminium engine components. Using the wrong coolant — or neglecting to replace it — can cause significant damage.

Types of Antifreeze

There are several formulations of antifreeze, and they are not universally compatible. Mixing incompatible types can cause the inhibitors to react, forming a gel that blocks radiator passages. The main types are:

IAT (Inorganic Additive Technology) — traditional green antifreeze, used in older vehicles. Change every 2 years
OAT (Organic Acid Technology) — typically orange, red, or blue. Used in many modern vehicles. Change every 5 years
HOAT (Hybrid OAT) — a hybrid formulation found in many European vehicles. Often pink or purple. Check your handbook
Specific manufacturer formulations — BMW, Mercedes, VW, and others specify particular coolants; using a generic type can void warranty

The Correct Concentration

Coolant should typically be a 50/50 mix of antifreeze and water, protecting to around -37°C. More than 70% antifreeze actually provides less frost protection — the optimum is 50%. We test coolant concentration using a refractometer during every service.

When to Change It

Coolant doesn't last forever. The corrosion inhibitors deplete over time, leaving bare metal surfaces in the cooling system vulnerable to rust and electrolytic corrosion. Most manufacturers recommend a coolant flush and refill every 3–5 years depending on the coolant type.

At PKA Automotive, we use manufacturer-correct coolant formulations and carry out full cooling system flushes to maintain your vehicle correctly. Ask us to check your coolant at your next service.