I was thinking about this earlier....What does synthetic oil have that dino oil doesnt given this senario: If synthetic oil is changed say around 6,000 miles versus dino oil being changed at 3,000 miles, wouldn't the 3,000 miles interval of dino oil be advantageous considering that over time, water, soot, dirt and other harmful elements would be suspended longer in the engine. Since the average person drives their car about 12,000 miles a year, that would mean 2 seasons would pass before the average person changes their synthetic oil at 6,000 miles. (this is the case if you live somewhere where you have 4 season). I just figured that since the engine is not exactly a closed system where the effects of mother nature can take its toll inside the engine by introducing water, dirt, etc., there may be advantages of changing oil sooner than 6k. Especially on those late winter/early spring nights where temps can sometimes be close to the dew points and the air becomes more saturated with water....Just a thought at 2 am while I eat my Hot Pocket.