I did a search (honest) and did not find a good report on how premium diesel performs in the LLY engines. I know there are at least two popular ones. I can get Shell premium diesel around here. I have heard that BP/Amoco also sells a premium diesel.

Does anyone have any experience with these (back to back compared to standard #2). Are they worth any extra money? Does the engine run quieter?

Premium diesel can be labeled premium if it meets one of two specs. The NCWM spec (meet two of a list of specs), and the EMA spec (meet all of a bigger list of specs). IMO, the NCWM spec is a bit wimpy. The EMA spec is a real spec. Here are the details: http://www.chevron.com/prodserv/fuels/bulletin/diesel/L2_5_2_rf.htm

Here's what I can share with you guys about diesel fuel (I'm in the fuel hydroprocessing technology biz):

Cetane number is a measure of fuel quality as it relates to ignition delay in a standard test engine. Longer delay=increased emissions and noise. Short delay=quiet engine, lower soot, and lower emissions.

n-heaxdecane is the 100 reference standard compound. methyl-naphthalene is the 0 reference. A fuel that has the same measured ignition delay as a 50/50 (by volume) blend of those two compounds, is rated 50 cetane number.

Cetane number involves an engine test. Cetane index is a correlation that allows you to use API gravity ( version of density ), and the ASTM D86 T10, T50, and T90 temperatures. It lets you approximate cetane number using cheaper tests.

In the US, #2 diesel needs to have a 40 CN minumum. In Euroue it's higher, closer to 50, and as high as 55 in Sweden.

Aromatics (like methyl-naphthalene) increase fuel density and energy content per gallon, but lower the CN. Straight-run gasoil (from crude) has a very high CN (typically 60-80). Hydrocracked gasoil also has a high CN. FCC cycle oil (the gasoil boiling-range mix from a cat cracker) is usually very low in CN and high in sulfur. I've seen FCC cycle oils with densitiy as high as 1 and sulfur content as high as 2.5 wt% (25000 ppm). This stream is where most of the US CN reduction comes from.

In 2006, when the sulfur level in US on-road diesel goes down to 15 ppm, the CN should come up a bit. The only way to get sulfur levels that low is to do some saturation of the aromatics. That last bit of sulfur is usually held up in di-benzothiophenes, which have to be saturated and cracked open to desulfurize.

from what I have read on here from other owners, shell is among the worst to get. I proved it myself by switching to Chevron..mileage went up on the first tank.

I tried the Shell premium and the only difference I noticed was in the price. My best performance and mileage to date was the result of using Chevron and Citgo.

If you have access to Amoco Premier or BP Diesel Supreme, it's worth it. (WARNING: I'm ASSuming that they are similar since they are made by the same company & have similar attributes. See link below.) My local BP distributor delivers Diesel Supreme to my own storage tank, & I love it. I get around .5 to .75 mpg better fuel economy with it than regular #2, engine runs smoother, & claimed better lubricity (can't confirm that). It's good stuff. I ran my storage tank dry earlier this week, so I was filling up at Flying Js & Pilots, & my fuel economy went from ~19 down to ~18 on a couple of 327 mile round-trips to Cincinnati the last two days. I've tried other fuels labeled "Premium", but never noticed any difference compared to regular #2. Some of them already have an additive added, so I suppose that if you normally run an additive, you wouldn't need to then, thus it would be worth a little more per gallon.

This link (http://www.bpdirect.com/products/#p3) has some info on both the Amoco Premier & BP Diesel Supreme.

BTW, I don't know why the Diesel Supreme pdf says it's for off-road purposes only, since mine is taxed & un-dyed.

JM2C

I don't think Shell produces their own diesel. They buy from other sources. The Shell stations I buy from here in N Wisconsin usualy sell Artic Diesel or Gold. My family delivers Shell products. But, I get just as good of fuel mileage with the diesel that Shell sells, as I do Mobil, Amaco/BP, and even the fuel Fleet Farm sells. Worst is fuel bought from Quik Trip, SA, Conaco, etc.

I use Shell Premium here in San Antonio and it hit m $2.10 a gallon today. I haven't found any other premium here. Also use Schaeffers #139 Soyshield additive and like the combination.

I've been using Texaco/Shell since the first tank. We only have one grade. Here in SoCal today's low low price is 2.37/gal. :eek:

Hey Trip, do you goto the Texaco on the old road or The Shell on Secco?
Crap $2.37-:t Was 2.37 at Texaco?

After reading some of the stories about Citgo (which is at my Truckstop), I tried the local Holiday station for a few tanks ( I think the Holiday does decent volume). The truck definitly seems to idle smoother and does not seem to smell as strong. Maybe my imagination, but I will stick with Holiday for a while, which is from the Flint Hills refinery. http://www.premiumdiesel.com/

I use Shell Premium here in San Antonio and it hit m $2.10 a gallon today. I haven't found any other premium here. Also use Schaeffers #139 Soyshield additive and like the combination.
That's about what is here in Houston. I paid $1.89 today for Valero diesel.

finally here in austin, Chevron is about 1.89 thank god!!

Hey Trip, do you goto the Texaco on the old road or The Shell on Secco?
Crap $2.37-:t Was 2.37 at Texaco?
Texaco ($2.37)on the old road is my primary stop. Shell on Seco is my secondary.

:D

Been using Shell Diesel exclusively for over a year, I have 7,500 miles on my 04 LLY no problems. I have been averaging 19.5 mpg on the freeway unladen and 11.5 towing a 26 ft. weekend warrior. Today I topped of the tank it was $2.60 a gal here in Hemet Calif. ? Wow what do you think prem. Diesel would cost ?

Steve

finally here in austin, Chevron is about 1.89 thank god!!
which Chevron? I checked my two stations I get it from and they both went up. The Citgo was $1.99 and Shamrock was $1.93.. Everything else is over $2.. I live in south Austin...