Airhog panel filter and walmart/supertech/tech2000 0W30 synthetic in the Escort Wagon, took it from 29-31 tank averages to 32-34 tank averages.
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice
Synthetic oil in the engine will give a very slight gain. The biggest gain can be found by replacing the transmission fluid and rear axle fluid with synthetic. The oil industry has made major gains in increasing the lubrication abilities of modern oils.
The difference between mineral oil in say 1990 and Mobil One synthetic was pretty significant. The difference between off the shelf mineral oil today and Mobil One as far as gas mileage goes is minimal.
I run synthetic for the ability to extend my oil changes on my car.
Remember more air passing through the filter (K&N) the air mass meter will compensate by adding more fuel.
BTW I run paper filters in my car. I ran a K&N panel filter in my Turbo four for about five years and saw no gain in gas mileage. But when the Turbo seized
(247K) the front of the compressor wheel was covered with a oily grime. After I replaced it, I went back to a high quality paper filter and after 113K miles on the new turbo the front of the compressor wheel is still very clean.