Is ULSF as Safe for Diesel Engines as they say?

by Kevin Hamilton⁽¹⁾
Amsoil Diesel Lubrication

Seems like everyone is happy now that the new Ultra Low Sulfur Fuel (ULSF) is out. The environmentalists because they think they’ll have cleaner air. Big oil companies because they’ve got more reasons to keep the cost of diesel fuel high. Auto repair & service centers because they are replacing more diesel injectors and fuel pumps than ever. Seems like the only one who’s not happy is the diesel owner. So, what affect does the new ULSF have on a diesel engine. The results are not as minimal as you are lead to believe. The rigorous hydrotreating of diesel fuel to get 15 ppm affects the fuel in several important ways:

Loss of Energy (Mileage)

The processing required to reduce sulfur to 15 ppm also reduces the aromatics content and density of diesel fuel, resulting in a reduction in energy content (BTU/gal). Chevron tells you to expected a reduction in energy content of 1% and may affect fuel mileage.

Recent calls from disgruntled long-haul diesel drivers have stated much higher losses in mileage. Most diesel owners are reporting about 8-10%. Tim Riley, a VP of Operations at Exclusive Nationwide , an expedited delivery service states, “all of my 31 drivers have lost 2 miles/gallon in highway driving with ULSF."

Loss of Lubricity

Lubricity is a measure of the fuel's ability to lubricate and protect the various parts of the engine's fuel injection system from wear. Althrough s ulfur is not a lubricant, the process used to reduce the sulfur also reduces the fuel's lubricating properties. The severe hydrotreating removes naturally-occurring lubricity agents in diesel fuel . Fuel is the only conduit the injectors & fuel pump surfaces have for lubrication. The loss of lubricity in ULSF will expose metal surfaces in the fuel system and engine top-end to greater friction and wear. Exclusive Nationwide told us that last month alone, 5 of their diesel drivers had an average cost of $3000.00 in injector work done to their trucks. None of his drivers use a high quality diesel additive. D ealerships we spoke with say that since the fuel change, injector repairs have increased.

Loss of Corrosion Resistance

Equipment Manufacturers Institute (EMI) reports that ULSF can lose natural antioxidants that help prevent the fuel from forming gums & sludges. Antioxidant properties are vital in modern fuel systems that are exposed to higher operating temperatures. ULSF becomes less stable with the additional sulfur processing. "Fuel stability" is a term used to describe fuel's resistance to the formation of gums and insoluble oxidation products. Fuels with poor oxidation stability contain insoluble particles that can plug fuel filters. This may lead to decreased engine performance or engine stalling from fuel starvation. Oxidation is thought to cause the premature deterioration of older seal material and cause leaking of injectors when the sulfur content in diesel fuel is drastically lowered.

A Chevron bulletin tells us that a small number of vehicles may require preventative maintenance in the form of upgrading certain engine and fuel system seals that may not perform well in the transition to the new fuel and could leak. Studies of test fleets have indicated that fuel system leaks are not exclusive to a particular engine type, fuel type or geographic region.

SUMMARY The additional hydrotreating of diesel fuel to get 15 ppm affects the energy of the fuel, its lubricity, and its corrosion resistance properties. Big oil companies will tell you they treat the fuel to meet lubricity standards, but the only monitoring currently is to determine if the diesel fuel is high quality diesel fuel additive . A good additive provides injector & fuel pump lubrication, anticorrosion & seal protection, and restores fuel quality for improved mileage.

Articles used:

"ULSD could trigger other problems besides lubricity" by Jack Peckham

Chevron "New S15 ULSD Regulations"

Arthor Bio:

Kevin Hamilton was b orn in Ft.Worth, Texas in 1958 and spent much time with his granddad working on gas & diesel engines. After spending 25 yrs traveling the USA as a claims adjuster he became an independent Amsoil dealer specializing in diesel engine lubricants. He publishes articles and a monthly newsletter at his website PremiumDieselOil.com. His three great loves are the Lord, his wife, Kris, and his daughter, Tori.

Article submitted Sunday, April 01, 2007 & read 185 times.

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