In my last post, blogger "have a nice day" pretty much described the repair work my mechanic performed better than I could have described, so read his comment.
1. The oil pressure sender was replaced because it was leaking oil.
2. I have switched from Valvoline synthetic blend 5w-30 to Valvoline synthetic 5w-30. I have had problems finding the synthetic blend recently, so I thought now would be a good time to make the switch to full synthetic.
3. Lastly, I filled up with 91 octane (no ethanol) after getting the caravan back from the shop. I won't be doing this very often, but I thought it would be interesting to see any differences in performance compared to the 89 octane (10% ethanol) and 87 octane (no ethanol).
The following fill-up was achieved with 87 octane (no ethanol):
277.9 miles / 13.935 gallons = 19.94 mpg