Michael Mathe
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With Fewer Details Posted On The Pump, Diesel Drivers Have Little Indication Of The Fuel's Quality Or Performance

I can't tell you how many times I have stood at the #2 ultra-low-sulfur diesel (ULSD) pump and wondered just what I am getting out of that green-handled spout. This concern is heightened during seasonal changes from warm to cold when all diesel drivers begin worrying about fuel gelling. The regulations controlling what is posted at the pump are very different for gasoline and diesel fuel. When you pull up to a gasoline pump you at least know what octane fuel you are buying. Diesel fuel is different, but rest a little easier knowing there are federal regulations controlling certain performance properties of the fuel - they just don't have to post most of them at the pump.

Diesel fuel is a refined product of crude oil. If you performed a diesel fuel study and compared fuels across the country, you would find substantial differences in performance; however, you would also find that all fuel refineries meet a federally regulated standard for a few key fuel properties. The first is sulfur content. The maximum limit on sulfur content in on-road diesel fuel was reduced in 2007 from 500 ppm to 15 ppm, in accordance with the Environmental Protection Agency's Clean Air Highway Diesel rule mandating a 97 percent reduction in the sulfur content of highway diesel fuel. The new ultra-low-sulfur diesel allowed engines to be fitted with exhaust systems that emit less particulate matter and nitrogen oxide. Unfortunately, reduced sulfur in fuel results in increased wear in fuel systems and injectors. Sulfur in fuel acts as a natural anti-wear agent that protects fuel pumps and injectors from premature failure, so the reduced sulfur content left a hole that needed to be filled by lubricity additives.

Another regulation requires diesel fuel to have a certain level of lubricity out of the pump as measured by the high-frequency reciprocating rig (HFRR), a widely used friction and wear-scar testing system. For the HFRR test, the lower the number recorded (in microns), the more protection provided by the fuel. The maximum wear scar permitted in the U.S. is 520 microns. With sulfur all but gone from today's diesel fuel, refineries have started adding lubricity additives to ULSD to make up for lost wear protection.

The second key property is cetane index. This is a measurement of diesel fuel's combustion efficiency during ignition. The higher the number, the more easily and completely the fuel combusts. In the United States the minimum cetane value is 40. Fuel with a cetane number greater than 52 rarely delivers a substantial performance benefit in engines designed in the U.S. Because cetane values vary from region to region and cetane numbers aren't posted at the pumps, diesel operators have no indication which stations offer higher cetane diesel. If you get your hands on test data, optimum engine performance is found with cetane values between 46 and 50.

Depending on your winter driving conditions, the most important diesel fuel property may be its cold flow or its resistance to gelling in cold temperatures. The cold filter plugging point (CFPP) is used to determine the lowest temperature at which fuel will flow without plugging the fuel filter. Refineries accommodate seasonal changes by making a winter blend in which they mix the normal #2 ULSD with a percentage of #1 diesel (kerosene) and some cold-flow additives. Refineries increase the percentage of #1 diesel and cold-flow additives depending on region and temperature throughout the winter months to combat potential fuel-related cold-weather driving problems. There are no federally mandated minimum CFPP values that refineries must target for cold temperatures; and, unfortunately, fuel stations again do not have to post the cold-weather performance of the fuel at the pump.

AMSOIL has long recognized this variation in diesel fuel properties and offers several products that provide additional performance and security for diesel engines. AMSOIL Diesel Concentrate (ADF) provides both detergency to clean fuel injectors and the combustion chamber, and a lubricity additive to help lubricate the fuel pump and injectors to compensate for the lack of lubricity in ULSD. AMSOIL Cetane Boost (ACB) increases the cetane index for improved ignition performance and power. AMSOIL Cold Flow Improver (ACF) helps reduce the cold filter plugging point and protects engines from fuel starvation in cold winter conditions. In times of extreme cold, or when the fuel you purchased won't flow in cold conditions, AMSOIL Diesel Recovery Emergency Fuel Treatment (DRC) quickly dissolves gelled fuel and thaws frozen fuel lines and filters.

You can't guarantee high-quality fuel at the pump, but you can guarantee AMSOIL diesel fuel additives will make that fuel the best it can be to keep your diesel-powered application running at peak performance throughout the year. Published, AMSOIL Magazine 10/12. LLC is a large nationwide Dealer of AMSOIL Synthetic Lubricants and is now expanding into your area and surrounding states. If you have a business or are an individual with several vehicles, AMSOIL has several options available that may allow you to Purchase AMSOIL Products at Wholesale Prices. We can show you how to save money and extend equipment life with AMSOIL Synthetic Motor Oils, Lubricants, Filters and Fuel Additives. Please visit the AMSOIL Online Store for more information and to purchase AMSOIL Products.

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