Do You Need a Diesel Additive?

There is a great deal of confusion going on these days about diesel fuel as evident in the following e-mail:

Q: I pull a fifth wheel trailer with my 2001 GMC Duramax diesel. In RV Life magazine, March 2007, you say, “You also must put additive in diesel fuel to put back lubricating properties taken away by extra refining for clean air.”

The people I’ve talked to at my GMC dealership haven’t heard of this. What is your source on this and what do you recommend as the lubricant?

I talked to a diesel owner who was “filling up” and also putting Dexron II transmission fluid in with his diesel fuel. He said it kept his injectors clean. He didn’t have a Duramax.
Is this a good idea and if so how much and how often? Do you recommend something different to keep your fuel system clean?

Thank you,
Chuck Harbaugh, Milpitas, California

A: Growing numbers of people with diesel engines are experiencing fuel-related breakdowns and expensive repairs. To avoid these painful problems you need to understand the causes.
A very big change to diesel fuel occurred last fall. We are now using diesel fuel that contains a maximum of no more than15 ppm (parts per million) of sulfur.

Why is this change to ultra-low sulfur important?

Removal of sulfur from diesel fuel is good for the environment but comes with the potential for very significant costs to vehicle operators. It has been common knowledge since the change to 500 ppm “low sulfur fuel” back in 1993 that lubricity-enhancing additives are needed to keep destructive wear from shortening the life of fuel system components. The new diesel fuel with 15 ppm of sulfur is not a good lubricant for fuel system components. In Europe, there are similar low-sulfur regulations. But the European laws that require sulfur reduction also set a reasonable standard for lubricity so that the fuel should not damage equipment. In the U.S. ultra-low sulfur fuel is not required to meet the lubricity standard that the manufacturers of fuel injection equipment have published as the acceptable minimum for good longevity with their equipment.

The “Joint Fuel Injection Equipment Manufacturers Statement,” issued in June 2004, says that fuel system damage caused by fuel that fails to meet the criteria established by European Fuel Standard EN590 will not be covered under warranty. The American ASTM D975 specification permits about 13 percent more wear to occur, with the fuel still being considered OK from a lubrication standpoint. This creates a potential problem for U.S. diesel fuel users. The fuel supplied at the pump could comply with U.S. standards and still cause a wear-related failure that the manufacturer of your fuel pump and injectors will not warranty because the fuel you are using does not meet the published standard the equipment was designed for.
As a consumer you have no way to know if the fuel you are purchasing meets a particular standard. Fuel quality varies wildly, with many opportunities along the supply chain to become contaminated in some fashion. The manufacturer of your vehicle is not obligated to repair your vehicle under warranty if a failure occurs because of contaminated or low-quality fuel.
Fuel system repairs on a late-model diesel engine like Mr. Harbaugh’s Duramax can cost more than $5,000 if all injectors and the high-pressure pump must be replaced. The newer “common rail” fuel systems use electrically fired injectors that are very sensitive to damage from low-lubricity fuel, particulates and any water in the fuel. Significant data has been accumulated to show that use of Stanadyne Performance Formula stops damage caused by low-lubricity fuel while improving fuel mileage, controlling deposits, and assisting with removal of water that may be in the fuel.

We recently made repairs at the PowerShop to a 2005 Dodge diesel pickup, which had an incident of very bad contamination by particulates in the fuel. Our customer purchased fuel while traveling in Montana and then had his engine stall within a few hundred miles. The fuel filter was found to be completely plugged with gritty dirt. The filter was changed and he continued on his way but soon the engine would not start. Dodge denied warranty coverage because they concluded that the damage was caused by contaminated fuel, so the gentleman had only the two most affected injectors changed and brought the vehicle to us for completion of the work. Either the fuel filter failed to do its job or dirt was permitted to get past the filter when the filter was changed, but regardless of the reason, damage was caused by low-quality fuel and this very expensive repair was not covered by the vehicle warranty.

There are hundreds of products in the marketplace that claim to improve the lubricity and performance of diesel fuel. Stanadyne Performance Formula is the only one that has been recommended in service bulletins from vehicle manufacturers, including GM, and also from fuel system equipment manufacturers as effective treatment for the lubricity issue. With all the choices out there, how do you know which additive is best? With what is at stake, this is not a place for trial and error. We know that Stanadyne Performance Formula works.

It just makes sense to do very good fuel-filter maintenance with high quality parts, use Stanadyne additive in every tank and to consider adding an appropriate pre-filter to your vehicle for a second line of defense for your expensive fuel system components.

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E-mail questions to askchuck@thepowershop.com. Chuck Arnold is one of three founders of The PowerShop in Enumclaw, Washington, where he helps RVers with their diagnostic, maintenance, repair and performance enhancement projects. Chuck has authored hundreds of RV articles and is a frequent guest on the Northwest Auto Show, which airs on Seattle radio station KVI Saturdays from 6 to 8 a.m. Recommendations in this column are general in nature. Vehicle owners should seek professional guidance for specific problems.