start w/ the fuel filter. it's incredibly inexpensive and very simple to change on a chevy truck.

the tranny service needs to be done at some point, so if it's due...

clencher could be on to something. i looked at the recorded, yet very limited fill-ups and the previous 19.2 mpg in a 4X4 could be a stretch. and the recent fill just balanced an inflated number.

The trans fluid is pretty fresh. I have a slow leak in the transfer case input seal which allows fluid to flow from the trans to the t-case, so I'm adding a fresh qt about once a month and draining the t-case down also. I have a seal, just havn't had the time yet. But, a filter change is going to get done soon, probably the same time I do the seal.

So, short fill-ups arn't good practice for FE huh? Well, thats good info, I'll keep that in mind.

Disappointed in my mpg, I went out tonight and installed a 75% grille block. I'll have pics of that up tomorrow.

run another tank or two and see what you get then.

Short fills aren't terrible, but they don't give you useful data like a fill from empty does. You have to average a lot of them together before their data becomes meaningful.

Good to know!

Heres my post on my new grille block: https://www.gassavers.org/showthread....423#post142423

How's your oil level? An overfull, or fully filled crank case uses more fuel than a half hash mark oil level. Jim

I recently had a 1 MPG drop off after three tanks of 18.9 MPG. Asked Leon, who runs the Costco station about Winter Blend and he said my mileage should increase with it. But we don't have it here yet.
Supporting OPEC to the tune of $40.00 or more a day, I've gotten pretty good at the art of topping off, but as the experts previous to me have said, as complete a fill as possible is most accurate, as is more than one tank of gas.

With all due respect to Leon, up till now I've only seen and heard of mpg dropping off with winter fuel mix and coming back up when we go back to the 'summer' stuff. I track mpg with every fillup and I've seen it every year since I started in Feb. '07.

I'm sure some of the winter decrease is due to sucking off engine heat to stay comfortable inside the cabin. But I think the fuel change is a big part of the reduced winter mpg's I've seen.