Emergency Coolant Type Mixing Guide for Different Colours (OAT vs. HOAT vs. IAT) | MyMechanic Malaysia
Watching the temperature needle climb on a Malaysian drive is never fun—worse still when only the “wrong” coolant is nearby. This practical guide covers IAT, OAT, and HOAT differences, what mixing does, and safe emergency steps—plus how coordinated roadside help keeps SG cars protected without guesswork.
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?
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.
Rule of thumb: stick to one coolant family whenever possible.
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.
Why MyMechanic is the right partner
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.
Overheating now? MyMechanic coordinates safely across Malaysia
Share your KM marker/landmark, plate, and symptoms. We align safe staging, checks, top‑ups, or towing—without publishing prices or addresses.
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.
