Improved mileage on 2000 GC 3.3

Charlotte, NC
Well, the numbers are in. We have a solid 1.5 to 2 mpg increase across the board this year. Wife reciently commented about better mpg with her commute. Last year she was consistently getting 19.5 mpg week after week. This year she is getting 21 to 21.5 under like conditions. We did a day trip to Columbia, SC today. I recorded 28.4 going, some tail wind and no AC, speed was 60 to 65 mph. Return trip I got 26.5 mpg with a headwind and running the AC. last summer I started using LC20 and F60. In early Sept. I changed the Trans fluid, replaced the sparkplugs, and did OC with M1 10W30. The next week we took trip to Florida. Got 25.4 mpg going down and 24.7 on the return trip. About 6 weeks ago with ~7000 miles on the M1, I added a full bottle of Auto-RX. Changed the oil Sunday with 8500 miles on it. For the rinse I filled it with 4qts. Formula Shell 5W30 and 1qt. Rotella T 15W40. Will be watching the mileage closely for sure now.