interesting conversation about draining oil

[dave]

Your riding buddy has some interesting points, here are my thoughts: Detergent oils work by trapping the dirt and returning it to the filter to be removed (the larger particles, anyway). When your buddy allows his bike to sit overnight before changing his oil the dirt particles trapped by the oil all settle out, to the bottom of the oil pan. When he drains his oil do all of these dirt particles wash out? Nobody can really answer this question. By starting your engine and allowing it to warm to operating temperature the oil will pick-up all these dirt particles and suspend them, and I believe resulting in a more thorough removal of the dirt when you drain the oil. The warmer oil temperature will suspend more dirt also.