Oil doesn't wear out, it gets dirty. Today's oils have detergents in them to help keep the engine clean. However, the detergents wear out after about 3K miles. At that point, dirt and deposits begin to build up in the engine.
Will oil last 7500 miles, yes. Would I recommend changing it every 3K, yes because it will prolong the engine's life. Also, because of where you live, moisture becomes an issue during the winter months. Keep it changed.
Let me know if you have other questions.
Thursday, October 21st, 2010 AT 10:06 AM