Smoke coming out of exhaust on a car

Can someone help me settle an argument we're having at work? Whats the difference between White and Blue smoke coming from the exhaust.

Thanks

Edit: Its not my car (thank god), will pass on any info. thanks for all the help.

White smoke, not always too much of a problem, may even be general vapour.
Blue smoke usually indicates that the engine is burning oil......and not in a good way!

Yeah my old car had blue smoke on startup, found that my oil level kept getting low. Kept topping it up until i managed to sell it.

As above.
Blue smoke is often an indication that a piston ring or seal has gone, and soon your car will drink as much oil as it does petrol!

White smoke can normally just be water vapour.
Excess white smoke though, is usually an indication that water or anti-freeze has got in to the cylinders. Headgasket failure. Check of the oil filler cap will show a white gunk around the cap area.

Cheers guys, guy's daughter has major white smoke issues coming from the exhaust when engine is warm. Mechanic said it was excess fuel entering the system and she requires a new ECU, I however disputed this and said the same as you guys. (Not that I really know what I'm talking about )

(Not that I really know what I'm talking about )[/quote]

That makes two of us.

Originally Posted by andyb

Cheers guys, guy's daughter has major white smoke issues coming from the exhaust when engine is warm. Mechanic said it was excess fuel entering the system and she requires a new ECU, I however disputed this and said the same as you guys. (Not that I really know what I'm talking about )

Sounds like a blown head gasket to me. Is the car also lacking in performance?

Check the coolant (is the level low and is there an oily residue there) and like Gnome said, check the oil filler cap for mayonaise (white gunk)

Excess fuel (if it's a diesel) would be Black smoke (and lots of it) (petrol, I'm not so sure about as I've never dealt with fuel injected petrol engines, but you would get a very strong smell of unburn petrol from the exhaust).

I'd say this garage is trying to rip her off. Take it to another one which you know is reputable.

lots of white smoke? id be looking at Head gasket too.

I'd be looking to sell ASAP. or P/Ex

Originally Posted by Tim in Belgium

I'd be looking to sell ASAP. or P/Ex

Indeed... From experience, cars are never the same again after the head has gone... At between £400 & £600 for a repair (at a garage,) they are expensive