Emergency Coolant Type Mixing Guide for Different Colours (OAT vs. HOAT vs. IAT) MyMechanic Malaysia

The three main coolant types

• IAT (Inorganic Acid Technology): Commonly green; used in older vehicles; shorter life 2–3 years.
• OAT (Organic Acid Technology): Often orange/red/purple; standard in many modern cars; long life ~5 years.
• HOAT (Hybrid OAT): Frequently yellow/blue/turquoise; blends IAT and OAT traits; designed for alloy engines; long life ~5 years.

What happens if you mix them?

Rule of thumb: stick to one coolant family whenever possible.

• IAT + OAT: Poor combination—risk of sludge formation and clogged passages.
• IAT + HOAT: Risky—additives can counteract protection.
• OAT + HOAT: Less dangerous but still sub‑optimal—reduces long‑term effectiveness.

Emergency steps on the road

• Stop safely: Hazards on; let the engine cool. Never open a hot radiator cap.
• Distilled water top‑up: Preferred temporary option if the correct coolant isn’t available.
• If mixing is unavoidable: Match type/colour if possible, add only enough to move, then plan a full flush.
• Persistent heat or leaks: Request assistance to prevent engine damage.

• Help tuned for SG‑registered cars across Malaysian highways and towns.
• On‑site support for overheating, leaks, and safe top‑ups where appropriate.
• Fast coordination to cut downtime and risk when temperatures rise.

Final word

Mixing coolant types is a last resort; water is often the safer temporary bridge. If temperatures won’t stabilise, pause the trip and coordinate help. With MyMechanic, SG drivers in Malaysia get steady assistance until a proper fix is in place.

Frequently Asked Questions