I have a 95 Club Wagon with a 5.8L engine. I've noticed that the engine consumes more oil the longer it is left in service. When the oil is fresh, the engine uses none for the 1st 1,000 miles. A couple of ounces the 2nd 1,000 miles. Upto a 1/2 quart the 3rd thou. And from 4-4,750 miles recently, it used a full quart. Seems to follow the same pattern regardless of brand, or type of driving. Why is this?