I just bought a 2008 Audi A4 with the 2.0T from a dealer. After purchasing the car the low oil light came on. I assumed it just needed an oil change. 2 days after changing the oil the low oil light came on again. Checked the dipstick and it was low. I've noticed that when I punch the gas pedal a flume of smoke comes out of the exhaust and when i let off the gas pedal it stops. Doesn't feel like the car is losing power and its not making any suspicious noises. Any suggestions as to what it might be and a price on what I'm looking at to fix it?