...the oil in my 4.7L Toyota. I have 3K miles on the current oil, M1 10W-30 with M1 filter. The vehicle has 12K miles, and I had planned to go 6K on this oil before changing and doing an analysis. However, when I recently checked the oil it looked visually dirty. Since I have been changing my dino oil every 3K for the last 30 years, my natural reaction is to do an oil change now. But, from reading this site, I know I should be able to go with a longer drain interval. Is a dark colored oil a reason to change, or am I just an old dog trying to learn a new trick?