I just drop by Walmart and get some mobile 1 and stop by a place that works on cars, I prefer country I know they will help, ask to borrow a spot and a pain to catch the oil. Change it right there. On trips planned that long I either carry a filter or make arrangements some where and have it done. There's a lot of ways to get it done. When you live on the road fer some time you learn a lot of short cuts. Haven't forgot them.
Mobile 1 for me too.