1998 Mitsubishi Eclipse oil burning

I have been driving this car for three months and it does not seam to burn oil when I drive back and forth to work but when the car idles for long periods of time it starts burning oil bad but if I drive it around for a little it stops smoking. The check engine light is not on and I check the oil almost everyday and it only seams to burn oil when I get stuck in traffic or let it ilde. Any clue what would be doing this