I'm a new diesel owner (other than my JD tractor). Recently in Tennessee, I pulled into a truck stop and got confused because I had my choice of Diesel or D2. I think the D2 was a good bit cheaper.

Since I wasn't sure which one to use, I went down the street to the auto/convenience store and filled up at the diesel pump. I noticed after filling up about half way that the pump said "D2".

At my home station, used often by the big rigs, my pumps don't say either.

Best I can find from my research on the internet is that D2 is winter blend, less refined, and has an additive for preventing cold weather gel (one site said wax) in the fuel. But I also read on another site that D2 would get better mileage. However, everything else I read says that winter blends get worse mileage.

So at this point I'm just confused and doing a search on this site doesn't come up with anything.

05 F250 crew FX4

 

There is some good information on fuel types in this thread. I doubt that you would find #1 that far south, but you could make a liar of me yet.

 

I think I've got this right, I'm sure I'll be corrected if I'm wrong, but D2 is standard diesel fuel found at most pumps in the summer. D1 is the diesel that has more antigelling capabilities,
however it has less power too. Winter fuel is typically D2 mixed with D1. I believe the refineries add more D1 to the mix as it gets colder and less as it warms. Hence more mileage in summer than with the winter blend.

 

The difference between #1 and #2 is in the amount of refining.

#1 is very similar to Kerosene. It has a lower BTU rating than #2; less usable energy. By its nature, it is not as likely to suffer from wax seperation in cold temperatures. This fuel is usually found in arctic climates.

#2 is standard diesel fuel. It is the most common fuel.

Winterized or Climatized diesel fuel has additive packages that help prevent wax seperation. Think of it in terms of adding Powerservice or Howes in bulk. It is not necessarily a mixture of #1 and #2.

Preimum diesel is #2 with a minimum cetane rating of 49.

 

I searched and found this information out of an old post which I made. Here is the link to the original post it was in https://www.ford-trucks.com/forums/s...ghlight=diesel

It is preferred to run #2 diesel to achieve better fuel economy. Diesel fuel in general is a heavier petroleum distillate than gasoline and because of this it has a higher flash point. Due to the refining process, the flash point of #1 fuel will be lowered, and as a result offer better cold weather starting in a diesel compression engine. Since #1 diesel is more refined than #2 diesel, it has less paraffin (ie.: wax) dispersed in it. The paraffin will begin to gel as the ambient temperature drops until it no longer flows, which is approximately 0F for #2 diesel, but can vary by fuel brand or additives. Premium diesels may have additives to keep the paraffin dispersed and prevent gelling, boost cetane levels, add lubricity to the fuel, and/or clean injectors. Premium diesel can vary by distributor since it depends on the additive and concentration of the mix.

In diesel engines, fuel economy is related to the heating value of the fuel. This heating value is measured in BTU’s (British Thermal Units). #2 diesel has a higher density (7.05#/gal.) than #1 diesel (6.76#/gal.). The denser fuel (#2) has more hydrogen and carbon molecules remaining from the refining process thus offers more energy per unit of fuel. #2 diesel has ~140,000 BTU/gallon vs. #1 diesel’s ~135,000 BTU/gallon (FYI: gasoline has ~124,000 BTU/gallon).

Diesel by spec is required to have a minimum cetane number of 40. The cetane number is a measure of how quickly the fuel begins to burn (auto-ignite). The higher the cetane number, the quicker ignition will occur. Most diesel has a cetane range of about 40-46 and premium diesel will be in the 45-50 range. It has been reported that diesel fuel reaches a plateau and will not benefit from raising the cetane number greater than 50. Most diesel additive with cetane boost will raise the cetane number 4-6 points. This will bring standard diesel into the premium range. My personal research has shown that a diesel additive with antigel additives and a 4 cetane boost adds ~$0.035 per gallon and a diesel additive without antigel additive and a 6 cetane boost adds ~$0.035 per gallon. This is about the difference you see from regular diesel to premium at the pump.

The semi-trucks that run here in the winter months utilize #2 diesel fuel year around for better fuel economy. They also have to use fuel additives or fuel tank heater (electric or engine coolant based) to keep the fuel from gelling. The diesel additive with antigelling properties can lower the pour point as much as –30F. This would allow you to run #2 fuel with better fuel mileage results and still have cold weather operability. Personally I have to run #1 fuel in the winter because it may get as cold as –40F to -60F. I still add the fuel additive for increased cetane levels and more lubrication to the fuel system (fuel pump and injectors). I switch to #2 fuel as soon as I can without the risk of cold temperature gelling my fuel. I have heard of as much as a 30% reduction of HP on a dyno running #1 vs. #2 fuel. Some areas that may not get as cold can offer blends of #1 & #2 which lower the pour point to a safe level and still maintain some of the fuel economy benefits.

I hope this information helps everyone. It was my own research from sources from which I deem credible, but take it for face value. Chevron has some good information on their website (http://www.chevron.com/prodserv/fuels/diesel/) and so do some of the diesel fuel additive companies. I currently have only tried 2 diesel fuel supplements and do not have any hard evidence (dyno or emissions testing) to favor any particular one, but have had good results from both.

 

Ditto the above (eaiser to say then type). I do notice about 2 mpg better with #2 but thats my experience.