Diesel fuel mileage

Has anyone else seen a drop in fuel mileage in their diesel trucks in the last 5-6 months? Reason being my 06 Dodge I checked around thanksgiving got 19.7 on a thousand mile trip, usually around town 17-18. Last 3 times I’ve checked it’s now 14.6 and consecutive checks this summer. 134,000 miles on truck and still runs great. Not using that lie gauge either, actual gallons into odometer miles. In 15 years it’s never got that bad of millage. Do you think the cetane rating has dropped

Yup , and depends on how much Bio-Fuel they are pumping into your diesels fuel in your area . NOT supposed to go over 20% . but they always do . R

Wow, never head of that but would explains the down side. Thought of adding 2-3 gallons of gasoline to every tank full to ‘spice’ it up a little

Around here that happens every winter when the stations go from #2 to a 'blend' and then to #1 if it gets cold enough to take the brass monkeys indoors. The cetane rating drops accordingly.

I’m averaging 20.5 mpg in my 07. Had a complete fuel system flush back in May. Anyway, in June I hauled a 69 RR UP TO Washington averaging around 14.5 mpg and coming home hauling my 52 PU with an average of 15 mpg. All this was had calculated verifying the Lie O Meter. Did a trip up into the mountains in July and got 22 mpg. I just turned over 317k miles and since buying the truck haver gotten that type of fuel mileage. By the way, the fuel system flush was a BG product.

My lie gauge is off 6-8 mpg. Did you check actual odometer readings with gallons?

So 20% bio fuel makes MPG go down 25% ??? Something don't add up there especially since some guys run 100% bio fuel and don't get significantly different MPG...

Timing of the injection pulse(s) and then the addition time before the fuel burns
has a key effect on diesel fuel economy.

Timing has already been retarded from optimum to reduce NOx.

Cetane rating only partially measures this,
but certainly the easiest step for an owner to experiment with is to add an aftermarket additive Cetane improver.

Diesels are only around because
the first prototype engine ran SO MUCH better on peanut oil
than talcum power sized coal dust, which is the “free fuel” that Rudolf Diesel’s coal miner uncles urged him to build a engine for.

Sometimes it seems the government is trying to make owning a diesel such a pain that you go into despair and jump off the stern of a fast moving ship into near freezing sea water.

Sounds like the ethanol ploy is moving over to Diesel fuel.
Hey it worked on gas, lets do diesel now.
We'll sell it at a cheaper price initially to entice the idiots to buy the cheaper fuel. They won't realize that although it appears cheaper, they're using more as the MPG drops. So we'll sell them more ethanol fuel at a higher profit.
Then we'll jack the price of the non ethanol fuel up to make it's cost equal to the ethanol garbage.
The consumer will start using the ethanol and we make more $$

It doesn’t, biodiesel doesn’t provide a significant fuel economy shift (it isn’t like ethanol in a gas engine). Something is wrong with the original poster’s truck, I’m guessing it has an injector on its way out.

Oh Oh, I don’t wanna hear that. $$$$

Isn't #1 diesel fuel the same as jet A fuel and or kerosene ? Or is that #2 diesel fuel?
I saw a distinct drop in fuel mileage when they changed from the old diesel mix to the current low sulfur mix around 2 MPH on the road and in town

Don't know. I am relatively sure that #2 is similar to home heating oil. When I worked in a gas station years ago we didn't have diesel but we had what Enco called "#2 burner" which we delivered for home oil furnaces.

When was the last time you adjusted the valves on it?

If they've never been done, that might be where at least some of it went.

Any 3406 CAT engines I had were real fussy with valve settings. They called for .015 and .030 and they didn't mean .014 and .029. Fuel mileage would suffer by a few tenths.

Kevin

I can not remember if Jet A was 1 or 2 but we ran Jet A but added one quart motor oil to it per 10- 15 gallons Jet A. Did not run it drier tgan 1 quart per 15 gallons. We did pick up mialge but ran just as good as summer fuel we get here in the south I never ever ran winter. But was offered at the truck stops cost was more $.
When I got my 1st oil burner fuel was $0.49 gallon

When I used to haul fuel back before the advent of ultra low sulphur, there where only 2 pipes you loaded from, #1 and #2 distillate.

#2 could be called #2 diesel, colored #2 diesel or furnace oil, depending on the end user. #1 was #1 diesel or colored diesel, kerosene or stove oil.

Jet fuel was also #1 but more refined. It was also known as Water White Kerosene. I used to haul it out of Fulton NY but never as Jet Fuel.

The price would change depending on what the product was called, not what tank it was pumped from.

It was and still is quite a racket.

Kevin

134,000 and covers have never been off

You should set your valves. I set the valves on my 01 when it reached 100,000 miles. I found the lash all over the place, being loose or tight. There wasn't one valve that was in spec. It did seem to run fine before the valve lash, but never kept a record on fuel mileage.

The owners manual with my 1994 Ram 2500 said cold weather you could run lerosene but had to add motor oil 1 quart per 10 gallons kerosene.
The military said same with Jet A in the Generators and trucks as it was to refined to add oil.
But tgat never came about at the base since thet had the right fuel to not have to substitute Jet A

Kerosene here is $5 a gallon, plus the oil maybe $6.50 @ 29 gallons, yikes!

OP’s 06 will have hydraulic lash adjusters.

I pulled the cover on my 01 at 150k…. Thought there was one getting loud, nothing was really even worth adjusting. Of course one came into work a week afterwords and I could hear the same noise. Forget what “normal” is sometimes.

I’m not a huge additive guy by any means but I’ve seen the CRC diesel fuel therapy do some pretty amazing stuff on the common rail trucks (03 up).

My VP pickup I use 2 cycle oil in the fuel (pint to 35gal)…. Gets so hot out here the newer fuels thin and you can set p0216 pump timing failure codes. Got this tidbit from Cummins.

I’ve used the 2 cycle oil before, Walmart brand low ash but I used a quart or more per fill up. I’ll also check out the CRC stuff. I put the 2 micron Cat filter & water separator filter add on about 3 years ago.