people that go by the color of the oil and say their oil looks good after 5000 miles . looks clear so they think that the oil is good for a while longer. the only thing that means is the oil is not cleaning the engine like it should. just like if you are washing your dirty hands and the water and soap look clear . but your hands are still dirty. the soap and water are not doing their job. would much rather see oil that is a little dark after 5000 miles. that means the oil is doing its job. of course oil also has to lubricate