Grey engine smoke
Put simply, when it comes to grey smoke, diesel cars tend to emit it when they lack enough oil. But there are other reasons why you might start seeing grey coloured smoke. Besides from being a sign of excess oil burning in your diesel engine, the smoke could also indicate:
1. A faulty PCV (Positive Crankcase Ventilation) valve
This part is responsible for emission control. It reduces the car’s emission as it draws unburnt fuel back from the lower part of the engine back to the top. Over time it wears out and causes the grey-coloured smoke. Repairing it is an easy and straightforward job.
2. Leak in the transmission system
If your car has an automatic gearbox then you should definitely inspect for leaks. If fluids are drawn into the engine through a leak it can cause costly repairs.
3.Jammed turbocharger
Burning excessive amounts of oil, slow acceleration and excessive grey coloured smoke are the typical signs of a worn-out turbo. The longer your drive your vehicle with a failing turbo, the more damage you cause to your engine and therefore the most costly it will be to fix.