This air dam mod may have just given a significant difference. The latest tank reads 22.49 and I noticed I didn't have to push the accelerator down as far when hill climbing that long hill between Brockway and Rigway and I also saw the fuel gauge go down considerably slower over the course of the tank. However, I'm not sure if the gas amount is quite accurate as the pump kept shutting off too fast and then it overshot at the end. I won't go to this station for filling this car up with gas as long as it does that.
I'm thinking of using a Renewable Lubricants' gasoline additive too:
I've been getting a lot of pre-detonation in this car even nearly 10k miles ago. The spark plugs and wires haven't been changed since 2011 (108/109k) and maybe this additive will help with that. If not, I'm going to either slowly pour water down the air intake or soak the cylinders in Seafoam because not only do I have pre detonation but the emissions out the tailpipe stink even when the car's been on the road for hours.
I'll report if the additive works not only in this but in other cars such as a Grand Caravan I never put in the garage on this site which should benefit from it and be easy to tell as it has a digital MPG gauge. This fuel conditioner is supposed to keep valves clean too, it's not only for fuel injectors. That one gallon's supposed to treat 2k gallons of fuel.
Hey, I have a wild idea. Perhaps I could take the electric fans off the dead 3.0 Caravan I now have and use them on the Caprice? I may have to still buy the thermostat but if it fits...?