Not really. I was never able to duplicate those mileage figures again. I suspect the fuel pump at that particular station may not have been accurate...(pump more but count less fuel) or operator error (I may not have filled up the tank all the way at the end of the return trip.

So, I would safely say the miles per gallon is not reliable, however....the percentage change should be (even if the pump meter at the station was faulty). Long story short, my fuel system probably needed a cleaning and running the Diesel Kleen did some good and the small mileage increase shows.

Since that post, I have logged about 180,000 additional miles on the truck and kept fuel mileage records the whole time. Basically the Diesel Kleen works, but isn't needed in each tank. Every 4 or 5 tanks of fuel does the trick to keep the system clean. I have been running Lucas in the in between tanks as well. So, I use both.

I just pulled my injectors after 242,000 miles and thought they looked pretty good actually. Each nozzle has 7 tiny jets. The nozzles were not clogged and free flowing on 6 of my injectors. The other 2 nozzles had 2 plugged jets each (only 5 jets spraying well), even then, the plugged jets did spray, but the spray pattern was not as strong as the others. I soaked those nozzles in a cup of Diesel Kleen for about 10 minutes and the jets cleaned right up, nice strong spray pattern.

I have a recent post running where I posted pics of the injectors when I first pulled them out. I thought they looked pretty good for nearly half a million miles. I think the Diesel Kleen and Lucas combo has been working for me, but that is just my opinion. I don't really have any specific knowledge of which is better or worse. I think anything that helps lubricate and has a cleaning agent should be ok to use.

Good luck!

 

Driving diesels and mostly diesels for last 20 years I would highlight the inconsistency in the test like that.
The originally quoted 3 mpg difference could be due the front wind on the trip changing from 45 mph to 30 mph.
Than the 65-70 mph cruising speed is leaving lot to desire. If you are at lower part of the bracket -you will get probably more than 3 mpg difference than at the top of the bracket.
I don't drive in city traffic too much, but per my records Bay Area freeway traffic is the biggest economy killer there is. My 35 mpg sedan, when driven here at 80 mph with constant gas and brakes fanning due to some idiots blocking left lanes barely makes 25 mpg.
That said on NY trip to Las Vegas I averaged 25 mpg going there and almost 30 mpg coming back. The higher mpg stays so far even in local driving. My driving speed didn't change, while the return traffic was much harder, still giving me 15% higher economy.
Unless something miraculously changed on my car -the only explanation I am coming with is that refineries in California switched from summer blend diesel (I suspect they add bio without admitting) to winter blend giving better mpg.

 

Actually, the summer blend will give better mileage than the winter blend because of how much volume the anti-gel additives consume in the additive package for winter blended fuels... in exchange for keeping the Cold Flow Pour Point low enough to prevent gelling in winter temperatures, they dampen combustion efficiencies.

Haven't read the entire thread, but there was an extensive third-party test performed several years back which has more consistent testing procedures, albeit this study only deals with the fuel lubricity issue alone and does not address fuel mileage gains at all.

Lubricity Additive Study Results - Diesel Place

 

Diesel fuel has changed since most of these posts wer done. In 2007 we swiched from LSD to ULSD, basically bringing the sulfer content down from 500 ppm to 15 ppm.

In addition to the link that Pete just posted, here is a link to the report done by Southwest Research, has some additional info.

http://www.natbiogroup.com/docs/educ...%20results.pdf

 

I believe it's the same study, Rich. At least it looks almost identical at a glance. Regardless, you've hit the actual report itself instead of a copied version in a forum thread, and your link includes the research company information which is good to have. Thanks

 

Here is a link to sign up as a Xp3 distributor, that is the only way you can buy it presently.

FuelDirect

 

Here are some testimonials, 3.4 billion in sales last year with Xp3
People love the product.

Xp3 Testimonials