Help with diesel terminology - PeachParts Mercedes-Benz Forum

WhoWhat · #1 03-28-2009, 07:43 PM

I usually fill up near my house at a Speedway gas station - they have the ULSD at two pumps. Yesterday, I was away from home, and filled up at a station where it listed the diesel fuel only as #2.

I understand #2 to be the designation for diesel as it relates to other fuel oils; is the ULSD also #2, or another grade of diesel fuel altogether? Can diesel fuel be ULSD and #2 at the same time?

Jeremy5848 · #2 03-28-2009, 08:00 PM

Yes it can. Diesel comes in two flavors, #1 and #2. I don't know the chemical difference but diesel engines usually use #2 except in very cold weather. Diesel #1 is similar to kerosene in that it is thinner than #2.

ULSD just refers to the amount of sulfur (an impurity left over from the oil out of which diesel is refined). Burnt sulfur is a pollutant; ULSD has very little, older versions have more sulfur.

bobodaclown · #3 03-29-2009, 08:54 AM

No. 1 and No. 2 diesel fuels are made for use in highway vehicles. While No. 2 diesel is the more common of the two, No. 1 diesel is better for use in cold weather. This is because it has a lower boiling point and is lighter than No. 2 diesel. This makes it less susceptible to gelling or waxing in cold weather, and thus better able to flow through a car's engine. However, No. 1 diesel is more expensive than No. 2 diesel. This is why many people blend the two diesels together for use in cold weather conditions.

#1 is also thinner (less dense) than #2. (really)

Shawn T. W. · #4 05-15-2009, 09:59 PM

#1 has less parafin in it, less lubriction, when it was cold (like -20) we might add 10-20 gals of #1 to out #2 fuel tanks in our semi trucks, usually held total of 240 gal, don't run #1 straight for long . . .

pawoSD · #5 05-15-2009, 11:15 PM

Quote:

Originally Posted by WhoWhat

I usually fill up near my house at a Speedway gas station - they have the ULSD at two pumps. Yesterday, I was away from home, and filled up at a station where it listed the diesel fuel only as #2.

I understand #2 to be the designation for diesel as it relates to other fuel oils; is the ULSD also #2, or another grade of diesel fuel altogether? Can diesel fuel be ULSD and #2 at the same time?

I wonder if we stopped at the very same station as you (last fall)......was it near Kalamazoo? We stopped at one that had "highway diesel only"....the high sulfur stuff.....according to the pump....the car loved it! Plus it was a little cheaper.....they had the ultra low sulfur stuff available too.....