It's a 1998 ford E-350. I change the oil every 3-5k miles depending where it's been. My question about the oil was, can I act like I did not drive the 5k miles since it was all highway and change it in 5k miles from now? It was going 62mph with no city driving all the way to Portland. So since highway driving is low wear on the oil can I wait longer to change it? That's what I was asking. As far as the idling I heard its good to let all the fluids "settle" in park before throwing it from drive to park and turning it off?
