I change the oil in my father in laws 1997 Ranger every 3 months. He will run about 4000 miles between changes. I have done this for over a year and have always used Chevron. Noticed on the last change that the new oil was much darker in color than previous changes. I assume that is due to the moly now in the oil? And maybe other tinkering? The old formulation was almost crystal clear. Hey this is a geat oil- I will get a uoa on the next change at the end of September. If I did not change his oil he never would.
and the truck would be this
But I am the only oil freak in the family so who cares