Is ULSD the cause of bad diesel MPG's

[Actros617]

I know it effects me because when LSD (Low Sulfur Diesel) was in the pumps i got at lease 23 to 25 mpg that's with out additives but with additives i got at lease 2 mpg improvement. But when ULSD Rolls in Oct, i started to see my mpg drop to 19 to 22 that is without additives, if i added additives i got better mpg say around 21-24 mpg. I know there is no fuel leaks because i send my car to dealer for fuel leak inspection...

anyways what do you guys think.....

Ps
It was done on a 300SD....

ULSD has a minimal effect on mileage, less than 2%.

[DieselAddict]

I saw no change with the transition to ULSD. Are you sure you're not talking about the transition to winterized diesel? That would make more sense. ULSD is a year-round fuel. Cold weather may cause a mileage drop as well.

[babymog]

DOE says 12%.

Originally Posted by babymog

DOE says 12%.

I would really like to see that reference, I have worked with about a dozen nuclear power plants that have reevaluated their emergency diesel generator capacities based on less than 2% reduction in energy content:

http://www.nrc.gov/reading-rm/doc-collections/gen-comm/info-notices/2006/in200622.pdf

In reality, some testing that I have seen shows no decrease in energy content.

[babymog]

Hey, there's the PDF I've posted here so many times, ...

The pdf I linked quotes a value of 1.2 %.

[Bob Albrecht]

Even if the energy content of ULSD is within 2% of the LSD there is still a difference in the lubricity of ULSD and LSD. The additives effect lubricity and this may be why you are seeing the mileage go back up.

I rarely burn diesel by itself, but I do know that biodiesel has significant lubricity advantages and that even though it has less energy content the mileage is similar even at 100% because of it, not to mention that better lubrication is better for you engine.

Some truckers, who purchased new trucks in 2007 and 2008, like to run 2-5% biodiesel or lubricity additive so they don't have to overhaul their engines as much.

[gsxr]

I've been chasing declining MPG since 2005. My MPG was excellent between 2002-2005, it slipped a little in 2006, and most noticeably declined in 2007 and 2008. I've been thinking something is wrong with my car. If it turns out to be crappy fuel, bow howdy, I'll be madder than a skunk dipped in perfume.

Anyone got a link to documents with the 12% info? All I've seen is the 1-2% claim. Maybe that was a typo with the hyphen left out...?

[Hatterasguy]

Originally Posted by gsxr

I've been chasing declining MPG since 2004 (most noticeably slid down in 2006 and 2007). I've been thinking something is wrong with my car. If it turns out to be crappy fuel, bow howdy, I'll be madder than a skunk dipped in perfume.

Anyone got a link to documents with the 12% info? All I've seen is the 1-2% claim. Maybe that was a typo with the hyphen left out...?

I have been noticing the same thing; back in 2004 when I first got my SDL the mileage was a rock steady 23.5. Now on this last tank I'm down to 20.5.

My driving hasn't changed and the car is in better shape now, so?

[Actros617]

really i dont see a 1.2% in reduction its more like 12% really my 300SD used to give way better mpg when LSD was on the market, with a full tank of Low Sulfer Diesel i can go from Tulsa to OKC round trip (200 miles) and still have at lease half tank of diesel left, now with full tank of ULSD i only get quarter tank of diesel, now that is not a 1.2% reduction its more of 12%, maybe its time that i should add some biodiesel and i bet its way cheaper than buying additives.....

Trust me, I've read enough diesel fuel test reports to know it's not 12%, actually it's often 0% depending on the process used to reduce the sulfur content. Lubricity has nothing to do with mileage, but if you are concerned about excessive fuel system wear use additives (personally, I think they are a waste of money but you should do what makes you comfortable).

If you are really seeing a significant decrease in fuel mileage you should do some basic troubleshooting and find the real problem; valve adjustment, IP timing, injector condition, timing chain stretch, compression, etc.

[Grdenko]

Im sure the difference varies widely based on all kinds of factors. Craig, from what you said it sounds like youre talking about ULSD in huge power backup generators, thats ALOT different than an old diesel benz on the highway. its a much bigger engine running at constant rpms.

But i also seriously doubt that %12 lower mileage is possible when all we have is anecdotal evidence. I also get alot lower milage on the highways than i did a few years ago, but i think a more likely cause is me having to speed up and slow down all the time because of all the people driving slower because of the high fuel prices!

[Bob Albrecht]

Originally Posted by Craig

Lubricity has nothing to do with mileage,

How do you know?

Why do I get the same mileage with biodiesel as I do with diesel and there is less energy in it?

Originally Posted by Bob Albrecht

Why do I get the same mileage with biodiesel as I do with diesel and there is less energy in it?

B20 and lower does not have enough difference to significantly affect mileage. B25-B100 is where the reduced energy content can be easily measured.