MPG question.

[Shield Arc]

But the main thing is those trailer tail gates are positioned to "scoop" the air when open. Look at them.

I'm going to remove the doors this morning for the return trip, it's just gotta help not having the "scoop"!

 

[Diamondpilot]

This is the issue with diesel fuel, there are no standards like gas. No "octante min rating". Diesel is rated in Cetane but the rating can very widely from refiner to refiner. Our diesel fuel in the states is junk when compared to what is available in other countries where its the primary fuel like Germany.

Chris

 

[Raspy]

It's hard to imagine a three MPG increase just from the fuel. What about the Siskiyous or the wind or your foot?

It is surprising how hard it is to pull those dump trailers! I think mine weighs around 4,500 lbs and it's wider than the truck.

Cetane ratings are about how easily the fuel ignites, not it's energy content, so mileage shouldn't vary much with a different number. And you had no way of knowing if one tank was higher or lower in cetane. Along the main corridors, like Interstate 5, and at truck stops, I think the fuel is pretty consistent. I've never seen a difference in mileage that I could say was caused by a difference in another state. I've even run all ratios of oil in mine. I even ran it for a while on son trip with straight lube oil with no diesel at all. Ran just the same as always.

 

[Shield Arc]

It's about 13-miles from Medford to Ashland, south of Ashland is where you start to climb, then you can watch the mileage drop! Yesterday on the return trip I filled up again in Medford, again the mileage went up. You don't hit any mountains for quite some time heading north out of Medford.

 

[MN Charlie]

With gasoline, different states mandate different "boutique" formulations and additives that even vary with the time of year. It's one of the reasons that fuel costs can vary so much from state to state (That and different taxes...) I wondered if diesel is subject to different formulations in different states too. Some quick searching turned up several articles about different states mandating new "low emission" diesel formulations so that could definitely enter into the equation.

I've noticed some pretty big differences in mileage on my gas engined truck depending on which state I purchased fuel.

 

[meburdick]

It's about 13-miles from Medford to Ashland, south of Ashland is where you start to climb, then you can watch the mileage drop! Yesterday on the return trip I filled up again in Medford, again the mileage went up. You don't hit any mountains for quite some time heading north out of Medford.

It's possible that the fuel you purchased in Medford could have:

- Been "fresher" (maybe they go through it at a high rate, turn the tanks over quick, and get their trucks from a very close port, etc)
- Had a slightly higher cetane rating than others, resulting in better burning efficiency (this is COMPLETE speculation based on my own personal observations that running premium gas in certain vehicles, under loaded conditions like highway driving, will sometimes yield better overall MPG).
- Had more lubrication additives allowing the motor to work more efficiently.

Dunno... Just complete WAGs at some things that *could* have been involved.