I have a 2006 Ram 3500 4WHD automatic with around 130,000 miles on it so far, I stopped earlier this year in January at one of the local chain oil changing places, they replace the Wix stock replacement air filter with their house brand that has a foam bottom on the inlet side of the element. I keep track of every fuel fill up and check the fuel mileage based on the trucks speedometer, it has got between 12.5 and 14.5 MPG around town before the air filter change. It went up to over 18.+ MPG with the new filter but I didn't think anything about it until I noticed the dirty air filter indicator on the stock air box showing it was dirty after two tanks of fuel so I reset it and it did the same thing in two more fill ups, around 2000 miles total on that element. I replaced that air filter with another stock Wix replacement type element and the mileage is now back to 12.8 to 14.5 around town after three tanks of the same fuel brand
All comments, inputs and your thoughts on this will be appreciated, Thanks

Is this an off road construction truck? What driving conditions plugged an air filter in 2000 miles?

Your engine is an air pump, and a Diesel especially a turbo diesel pumps a lot of air compared to a gas engine with its throttle plate..

The wix filter when new creates very little restriction in the intake tract. The oil change place filter may create a little less restriction at the expense of poorer filtration efficiency (and shorter engine life) but not enough to measurably affect fuel economy. The fact that it plugged in 2000 miles runs contrary to this.

Better recheck your math.

It wasn't plug that I can see, the foam bottom looks like it is a lot more restrictive to the air flow than the standard paper type Wix full size element is
I looked back on my fuel receipts from before the engine service in January 2018 and the last two fill ups since I changed that element, it definitely got better fuel mileage with that element from installation until I changed it
I live in central Oregon, Bend, where the highway departments put cinders and gravel on the roads in winter for traction on the ice which turns into smaller dustier particles after driving on them all winter long
My truck is stock, no mods at all, it is my daily driver and stays on the pavement 99% of the time, I live on a dirt road so I have to drive about 200 Ft on dirt to get to my rear driveway where I park it. I use the same source for fuel year round but we do have winter mix on diesel fuel here due to the freezing temps in winter, I use a fuel additive to stop the fuel from gelling in the winter but that doesn't always work when it gets really cold (-25F) here

Stick with the OEM---Save that engine

Gelled fuel? Got the 911 fuel treatment? People in NY can drive their diesels in the winter.

If you have biodiesel blend they gel at higher temps than straight diesel.

The liberal politicians and beurocrats(SP?) here in Oregon dictate to the fuel industry to make and sell bio diesel
Same thing on adding drinking whiskey to the gasoline in our state hurting fuel mileage but they get more income from gas tax due to the increased fuel consumption from every one having to use E10/E15 in their daily drivers

How did the foam pad look when you replaced the filter after the oil change? Was it wet?

It seems odd that it would max out the restriction indicator after only 2000 miles. A filter that restricted would be visibly filthy and if you blew compressed air backwards thru it, make a pretty big dust cloud.

In any case, resist the urge to install any K&N magic low restriction guaranteed to boost your fuel mileage type filter. There are only 2 ways to reduce filter restriction. Make the filter bigger or make the holes if you will in the media larger. Bigger holes = less filtration, more dirt gets in.

I just re-read you post. If the filter was pooched when you reset the indicator it basically should have maxed it out again after the reset the first time you stood on it and hit full boost. I asked above if the filter was wet. If water is somehow getting into the filter when it rains, it will restrict the filter and max out the indicator. Maybe by the time you noticed it, the filter dried out and was good until the next time it rained.

Can you burn 2 tanks of fuel in Oregon before it rains?

Kevin

Bend in on the east(dry) side of the Cascade Mtns. which block a lot of the rain the west side gets It does snow here and get cold in the winters though
I live around 4300 Ft elevation due to living south of Bend a little ways, Bend is right at 3300 Ft in the old downtown portion of town.
We get more snow and colder temps(-25F) along with a lot more big pine trees and critters like Deer, Geese, Raccoons, Mice and other animals due to the elevation
I'm going to put the stock Wix replacement air filter back in and see what the fuel mileage does for the rest of this year, winter
What I saw may have been abnormal due to something I didn't catch like the brand of fuel and location I bought it in
Oregon has more than one diesel blend is what I'm being told
I don't drive as fast in the winters as I do the rest of the year due to ice and snow on the roads around here so that may have some effect on the mileage also