I just had my truck into the stealer for the last of my free LOF's and had them replace the fuel filter while it was there. There is 22K miles on the truck.

When I gave it to them I was getting 17 mpg. 2 tanks in a row I have gotten 20 mpg. I commute to work with the truck so the driving before and after seeing the stealer is the same.

What gives? I'm not complaining but can that kind of basic maintenance make that kind of improvement?

What's a LOF?

Lube/Oil/Filter

Was this the first service on the fuel filter? My first filter was pretty dark already at 3k when I changed it.

This was the first service on the fuel filter. I didn't see it so I can't comment on the level of gunk.

I use Syanadyne every other tank and get 90%+ of all my fuel at the same very busy pump.

I'm just trying to learn something about my first diesel.

Somebody throw me a bone.