My 99, a3 seems to be burning oil at the rate of a litre every 2 months and theres a bit of white smoke coming from the exhaust

hi
White smoke is burning engine oil.
mostly when Engine oil is changed or topped up
little oil get dropped and when engine heats up. it burns the oil.
but once oil is burnt then no more smoke is there.

unless you have a leak
thanks

Possible cause is several drops of oil are leaking past the valve guide seals when the vehicle just sits. When it is started the oil begins to burn off in the cylinders and after awhile the smoke disappears. I have always recommended cha going the oil to a synthetic and adding an oil additive called Restore. It comes in a cylindrical can in 4, 6 or 8 cylinder size. Put 1 can in with the new oil. Drive the vehicle on the highway for 45 - 60 minutes. I recommend putting on a few hundred Mrs. The additive restores the valve seals preventing the oil from dripping into the cylinders. Have used it on my customers vehicles for 20 years. Saved them a lot of money from replacing the seals.

there`s only 2 ways to lose oil. one is a leak somewhere from the motor the other is the motor is burning oil. just because you don`t see smoke doesn`t mean its not burning oil. you don`t say how much oil your losing between oil changes. if its only about 1/1.5 litres between oil changes then this is a normal lose which means its burning slightly.

Typically bad rings, burning oil... when warms, metal expands, and seals better... check pcv system first, its cheaper, but generally will smoke at all times when bad... valve stem oil seals another posibility

White smoke is indicative of burning coolant. Gray smoke is burning oil.

Have a compression test done which will often give an indication of evolving head gasket problems. If the coolant level is going down, and there's no obvious leak, its a head gasket.

I'm sorry to say your engine may be cooked.
Since you are adding both oil and coolant, and the color of the smoke is gray or white, you have the signs of the engine burning coolant.
The common cause is a leaking head gasket.

Sounds like blown head gasket soery

Its the problem of oil.The oil is getting burned out. The vehicle is either burning oil or it is moisture in the gas chamber if you notice white smoke from the exhaust. This is a common possibility.but in some cases this white smoke is not due to oil burning.In that case   White smoke from the exhaust is a symptom of coolant entering the combustion chamber. Normally this is a sign of a blown head gasket or cracked head. And  this is not a common problem must be repaired immediately. You must STOP driving this vehicle or you will cause serious engine damage. you will have to get both this possibilities checked.
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head gaskets or rocker cover gaskets are leaking and burning on the exhaust

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