hi i have a 07 duramax classic it hac 109,000 kms andibought it 4 months ago i dont remeber hearing this sound when i bout it i makes a really light ticking noise at idle i went underneath lots of times 2 look and its comein right from the bottom end of my motor right inside the oil pan it dose it sumtimes then gose away very light ticking noise.its always been the same hasent been getting any worse can anyone help me dono what this would be.