It is no secret that oil degrades over time. The longer it sits, the less viscous it becomes. But how long is really “long enough”? When I went to a local mechanic, the TLC Auto & Truck Repair Service Center, the professionals said the modern engines need oil changes every 7000 miles or once a year. At the same time, some others said, every 3000 miles or every three months. … [Read more...]