2015 5.0 3.31. Just got a K&N drop in air filter. Avg milage went from 16.8 to 17.9 Truck is brand new and should only get better as truck wears,breaks in. Pretty happy with my purchase. I've put one in every vehicle I've ever owned.

 

I'm looking at getting a drop in filter too, probably go with dry one though. Never really been a fan of oiled filters.

Good to know that it improved your mpg because I just bought the same truck.

 

You're mileage increase isn't due to the K&N filter. I'm getting 18.5MPG with the 5.0L, 3.31, and OEM paper filter that came from the factory. All you are doing is passing oil and dirt into your engine with the K&N. The OEM paper filter will flow way more air than your engine will pull.

 

^^^This, if you're seeing an increase, it's probably from the break in of the engine.

 

OP...do a used oil analysis (UOA) on your oil after installing a non-OEM air filter and you'll likely note a significant increase in silica (aka dirt), a nasty engine wear agent. But, maybe the xtra 25 HP and awesome performance increase is worth the wear & tear.

 

 

I am averaging a tad over 20 mpg with a 5.0, stock filter, 3.31. Most all highway miles. Good enough for me. I have used K&N drop in filters before, but never found any advantage. No increase in fuel economy, no performance gain.

 

Last truck was a 08 f150 205,000 K&N from day one. No engine problems whatsoever!

 

No oil analysis is needed, never in 15 yrs ever had a problem with K&N. Like the gains!

 

What gains? Did you perform a rear wheel dyno prior to the installation and after the installation to compare? The 1.1 mpg gain can not be attributed to the air filter as there are too many variables that can effect that.