Cars wait at a traffic light with clouds of exhaust, showing how exhaust smoke colour can indicate your car’s health

It can be hard to tell when your car needs extra love and attention. Besides glaring dashboard warning lights, one easy way to measure your car's health is the presence and colour of exhaust smoke.

During the winter months, small clouds of white vapour after starting your car are normal and indicate that your exhaust system is cold. But large amounts of exhaust smoke, especially if it's a weird colour, may mean your car isn't running as efficiently as it could, and you should call your trusty mechanic ASAP.

Check if your vehicle is running efficiently with this quick guide on what different types of exhaust smoke might be telling you about your car:

  1. Blue smoke is usually a sign of burning engine oil. Piston rings in a car's engine help seal the combustion chamber, where air and fuel burn to power the engine. A worn or damaged piston ring may allow oil to enter the chamber, causing a lot of blue smoke to exit your exhaust when you start your car. Take your car to a mechanic as soon as you see blue smoke, as a broken piston ring can harm your car's performance and fuel efficiency. Cars that have been modified or turbocharged are also likely to spew blue exhaust smoke because of increased power output from the engine. This places more stress on the engine and increases the likelihood of oil leaks.

    You don't have to be a mechanic to understand what different coloured exhaust means. Keep an eye out for strange exhaust smoke to help diagnose any internal engine issues before it turns into a concern.

  2. Black smoke can signify incomplete combustion. Black smoke may mean your fuel is burning improperly in the combustion chamber because of low-quality gas, a lack of oxygen in the engine, or issues with your spark plugs or ignition coils. Black smoke from your exhaust generally contains more carbon monoxide and needs to be fixed quickly to reduce its negative environmental impact. Poor combustion also means your car isn't running efficiently, and the engine isn't producing as much power as it could.
  3. White smoke is usually from unwanted fluids in the combustion chamber. While white vapour is harmless, white smoke from your exhaust is the sign of a problem. The head gasket separates the oil and coolant systems in your engine. If a crack forms in the gasket from the engine overheating, fluids will enter places where they don't belong. Your engine will then combust water instead of fuel, which can cause catastrophic engine damage.

    Have you seen white smoke coming out of your exhaust? White vapour after starting your car is usually harmless as it's a sign your exhaust system is cold, but white exhaust could be a blown head gasket.

  4. Grey smoke could mean transmission fluid in the combustion chamber. Like blue smoke, a grey exhaust can also mean engine oil is burning. But it can also be caused by leaking transmission fluid. Transmission fluid keeps transmission parts lubricated. A broken transmission modulator can cause fluid to leak into the combustion chamber. Without transmission fluid, the metallic components of your transmission may start to seize, creating a breakdown in the near future.

Cars can be complicated, but knowing some of the warning signs of a mechanical issue can help you avoid a potential roadside emergency. Be prepared for anything that comes your way on the road by keeping your car stocked with these essential safety items.

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