Following are the Types of Car Exhaust Smoke:

1. Black Smoke

Black smoke indicates that the engine is burning too much fuel, a condition known as running rich. This can be caused by several factors that disrupt the air-fuel mixture.

2. White Smoke

It usually means that coolant is being burned in the engine, which means that something is drastically wrong. The most common cause of this is a blown head gasket, which can quickly lead to an overheating engine.

3. Blue Smoke

Blue smoke is a clear sign that your engine is burning oil. The liquid can leak into the combustion chamber where it is burned along with fuel. You'll probably notice your car misfiring when you turn the keys in your ignition, or find your vehicle shakes more than usual when idle.

4. Grey Smoke

If the smoke from the exhaust pipe is either grey or bluish-tinged, it generally means that your engine is burning oil inside the combustion chamber. Burning oil could be due to many causes, from leaky valve seals to bad piston rings.

Many thanks Steve.

One thing I would like to add, is to carryout this test only after a 10 mile run to ensure the vehicle is fully up to operating temperatures - particularly the engine oil. 
I get an assistant to hold the car at a steady 2000 rpm for at least 2 minutes - while the exhaust smoke is observed. 
Kind regards,

Gareth. 

18 minutes ago, Magnet said:

Many thanks Steve.

One thing I would like to add, is to carryout this test only after a 10 mile run to ensure the vehicle is fully up to operating temperatures - particularly the engine oil. 
I get an assistant to hold the car at a steady 2000 rpm for at least 2 minutes - while the exhaust smoke is observed. 
Kind regards,

Gareth. 

Sound advice Gareth 🙂