This recent rash of extremely cold weather has really driven home the importance of treating your diesel fuel with a good quality fuel additive to avoid diesel fuel gelling which will lead to plugged up fuel filters, cause potential damage to the fuel system in some cases, not to mention the royal pain in the butt it causes when our tractors, generators, or diesel trucks stall out at the worst possible moment. Ultra Low Sulfur Diesel a Concern in Cold Weather HARRISBURG, Pa. — Diesel vehicles in the region have been experiencing problems with fuel icing and gelling in the cold weather of recent weeks, according to a diesel fuel injection specialist based in Harrisburg. A major contributor to this problem is the new Ultra Low Sulfur Diesel (ULSD) with less than 15 parts per million (ppm) sulfur, according to Julie Miller of Miller Diesel, Inc. With ULSD, even the best fuel additives are only able to protect the fuel to approximately 0 to -15 degrees Fahrenheit in the region, Miller stated in an e-mail this week. The cold filter plug point (CFPP) — the point at which, during laboratory testing, fuel will no longer pass through a fuel filter due to temperature decrease which causes the fuel to thicken and “gel” — are starting in the +10 to +18 degree Fahrenheit range with untreated ULSD, making it a challenge to get the gelling temperatures well below 0 degrees Fahrenheit with fuel additives and/or kerosene. Prior to the introduction of Ultra Low Sulfur Diesel, a CFPP of -15 to -30 degree Fahrenheit was not a problem to achieve with the use of good fuel additives and/or kerosene, according to Miller. Many fuel retail stations and truck stops surprisingly do not pretreat their diesel fuel for winter operation, she said. Miller noted that using high quality fuel additives on a regular basis can help prevent icing and gelling and ensure trouble-free operation. However, troubles have occurred for operators that didn’t add the fuel additives until it was already too cold, she pointed out. Once the fuel reaches it cloud point, additives will not properly mix with the fuel until it warms up above the cloud point. This past October, the Bush administration required diesel users, including buses and trucks, to begin switching to ULSD. According to a Feb. 8 article in the Wall Street Journal Online, the problem comes during the refining process used to attain the ULSD ratio, affecting the naturally-occurring wax in diesel in such a way that it can cause the fuel to turn from liquid to gel more readily in cold temperatures. Gelled fuel clogs the fuel filters and starves the engine, causing it to stop. Regular low sulfur diesel users and offroad fuel users (including farm tractor operators) have also had troubles because of the low temperatures and water. However, ULSD is causing the most difficult situations, according to Miller. ULSD is not required for farm tractors at this point, according to Miller. She noted that some farmers may be receiving ULSD fuel and not realizing it. All 2007 on-road vehicles must use ULSD, or damage could occur to their engines. Miller said that good tank maintenance is a must. Operators must “take the situation into their owns hands” and not rely on the fuel supplier to protect them, she said. Good fuel additives year-round are “an absolute must.” Miller said that biodiesel has also proven troublesome during the recent cold temperatures. Factors contributing to this include some biodiesel being produced “off-spec” (not adhering to proper specifications) excessive water in the biofuels, poor fuel tank maintenance and lack of knowledge about properly using biodiesel. Miller Diesel, Inc. rebuilds fuel injection systems and is central Pennsylvania’s largest distributor of FPPF fuel additives.