2000 Burb Oil Usage?? Need Help! My wifes 2000 1/2 4x4 Burb is having problems. About a month ago, the check oil level light came on. Checked and was 1/4to 3/4 qts low. It was almost due for a change. Pulled it into the shop, dropped the oil and replaced. Didnt look bad and no water. Also no oil in radiator. Fast forward to today, she is driving and the check oil level light come on again. 1/2 to 3/4 qts low. Not in water and no water in oil. No spots under truck. No smoke on the vortec v8 with 80,000 miles. Is this normal usage? or major problems? All help appricatied.