That's obviously an "accidental repair." You would have had the same result if you put a new paper filter in there.
20 MPG on the freeway is normal. 12-13 MPG is broken.
my 4.10 geared 4.0 4x4 supercab gets 19-20mpg in "local" driving
and 21-22mph on the highway.
I agree, "accidental repair"
eric, you need to think of it in terms of energy. energy cannot be created nor destroyed, it takes X amount of energy to cool an engine under given conditions. it doesnt matter if the energy comes directly from the water pump pulley or directly from the alternator pulley. your doing the same amount of work either way.
I'll add to yuor comments.
To generate sufficient airflow through the radiator takes "X" ammount of work.
to do that DIRECTLY with a mechanical fan is "cheaper"
in terms of energy cost than an electric fan.
Because with an electric fan you must first take
mechanical energy and convert it to electrical energy,
THERE IS A LOSS HERE, then moved to the battery (where there is a further charging loss, then extracted to power the fan.
The only potential place for savings is that the electric fan doesn't run AT ALL until it's control circuitry (temp switch and relay) turn it on.
And the mechanical fan with a viscous clutch are spun
at partial power (with some wasted as heat) at the fan clutch.
Now everyone is going to point at that and scream at the top of their lungs "See I told ya!", here comes the bitch slap for being stupid... at PART throttle cruising operation the airflow through the radiator is already moving so the clutch doesn't actually slip all that much..., remember it's about the fan FORCING the air to move that requires power. if there is no "force" required (the air is already moving) the fan "windmills" to a greater degree...
Electric fans only sae with they claim to "save" at high rpm.
Anyne here who has ever driven with a fan clutch that has siezed, LOCKED-UP-SOLID knows that on upshifts the thing really howls, but in highway cruise you either barely notice it or don't notice it at all....
Frankly to avoid melting an engine I'd rather have a little too much cooling than not enough because if you fry your engine
the mileage that needs to be considered is that of the tow truck that tows you home.
AD