I changed oil in my brothers D/A last week; he had 23600 miles on the oil. I thought it was overdue to say the least, so I took an oil sample and sent it in to see how bad the oil was and if there was any damage to the engine. I got the oil sample back today and to my surprise it said no corrective action required oil is suitable for continued use.
With the above and other oil sample I have sent in on different vehicle, I'm convinced that it is safe to run oil longer than what the oil co. and car manufacturers recommend. I think they have us all brain washed with their recommendation and commercials. I remember the 3000-mile oil change was recommended long before I started to drive several moons ago. Seems to me it's pretty pathetic that they (oil co) are saying they haven't improved their products in that many years. That goes for the engines and air filters also. If we can safely run oil for 10000, 20000, or even 30000 miles why don't we. I know why; it would cut in to the big oil co bottom line, so they make sure they scare the h%$l out of us so we keep using there oil. Just think we could cut down on our dependence on foreign countries and save the environment from gallons and gallons of used oil, and save money in the process. That