Misfueling in Malaysia: Petrol in Diesel (and Vice Versa) — Immediate Steps

First Rule: Don’t Panic — But Stop Straight Away

Misfueling is more common than you think, especially when you’re traveling or hopping between different vehicles. In Malaysia, with varying pump designs and colors, mistakes happen easily.

The single most important rule? If you’ve put in the wrong fuel — don’t start the engine. If it’s already running, stop as soon as it’s safe. The less the wrong fuel circulates, the lower the risk of costly damage.

Petrol in a Diesel Car — Why It’s a Big Deal

Diesel engines use the fuel as a lubricant for the high-pressure pump and injectors. Petrol removes that lubrication, creating friction that can quickly destroy those parts. In extreme cases, metal debris can spread through the system, leading to an expensive repair.

If you start the car after misfueling with petrol in a diesel tank, you might notice:

• Knocking or rattling
• Loss of power
• Stalling or refusal to start
• Smoke from the exhaust

Immediate steps:

• Don’t start (or immediately switch off).
• Tell the petrol station staff — they’ll know how to make the area safe.
• Call a roadside service like MyMechanic to arrange a fuel drain or tow.

Diesel in a Petrol Car — Still Serious, But a Little Less Harsh

While not as destructive as petrol in a diesel engine, diesel in a petrol car still causes problems. Petrol engines ignite fuel with spark plugs, while diesel is designed to ignite under pressure, so it simply won’t burn efficiently.

You might experience:

• Rough idling or misfiring
• A lot of smoke
• The engine refusing to start

Immediate steps:

• As with petrol-in-diesel, avoid starting the car.
• Arrange for the fuel to be drained and the filter replaced before driving again.

How MyMechanic Gets You Back on the Road

For Singapore-registered cars traveling in Malaysia, MyMechanic offers fast, professional, cross-border roadside assistance. They know the urgency of a misfuel and have the network to get help to you quickly — especially in Johor and along popular travel routes.

• Come to you quickly if you’re stuck near a border or along the NS highways.
• Tow the car to a partner workshop if the wrong fuel has been circulated.
• Guide you step-by-step while you’re still at the station.
• Help with VEP-related matters if your trip was headed toward the checkpoint.

Step-by-Step: What You Should Do Immediately

If you’re still at the petrol station:

• Stop fueling immediately.
• Keep the engine switched off.
• Inform the pump attendant.
• Don’t try to “fill up with the correct fuel” — it won’t fix the problem.

If you drove off and just realised:

• Find a safe spot and pull over.
• Turn off the engine right away.
• Call MyMechanic for roadside or towing assistance.

Tips to Avoid Misfueling in the Future

• Always read the label and not just the nozzle color — different stations use different color coding.
• Stick a reminder on your fuel cap if you drive more than one type of vehicle.
• Slow down during refueling — rushing is usually when mistakes happen.

Frequently Asked Questions