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Fuel Q & A

Originally Published in Trailer Life Magazine

Diesel Fuel Primer

Q I am brand spanking new to diesel trucks, and my questions probably seem elementary to most of your readers, but I feel sure I’m not the only “new kid on the block.” Therefore, please consider providing a primer on diesel fuels.

On signs I see premium diesel fuel, diesel no. 1, diesel no. 2 and automobile diesel. What’s the difference? What do I need in my Ford Power Stroke diesel? The people who sell the different fuels can’t answer the questions except to say, “That’s what we carry.”

I’ve been told to buy diesel fuel only from high-volume dealers. That suggests to me that diesel fuel ages or deteriorates in some way and needs to be fresh. What should my concern be, with regard to freshness?

I have just received my first issue of Trailer Life and noticed two ads for “cross the bed” tanks. Are these a good idea? I would really like to be able to go more than 300 miles between fill-ups, especially when traveling in areas where diesel fuel may be hard to find.

I’m so poorly informed on these matters that I probably don’t even know the questions I should be asking. Please help out. Why I even bet there are a lot of old-timers who would learn from such a primer.

– D.B., Austin, Texas

A “Premium” diesel is a marketing tool and its formulation to “justify” the cost varies. It may have different additives for injector cleaning, or that affect the cetane rating for easy starting, lower cloud point for cold weather, lower sulfur content for cleaner burning, etc. It won’t hurt your engine to use it, although it will cost more. If you’re a person who likes to use premium fuel in your gasoline engine even if the manufacturer doesn’t require it, you’re a good candidate for premium diesel.

Always follow the manufacturer’s recommendations in the owner’s manual. No. 1 diesel is a thin, winter-grade fuel for extremely cold weather. It is less viscous and contains less energy per gallon than No. 2, so it should only be used when it is really needed. It can be mixed with No. 2 fuel.

No. 2 fuel is normally used in all but the coldest weather, when diesel fuel starts to gel and cloud up, and wax forms in the fuel filter. Depending on fuel additives, this usually occurs slightly above 0 degrees F with No. 2 fuel.

Pumps marked “automotive diesel fuel” normally have smaller refueling nozzles than those used to refuel large trucks, so they fit in cars and light trucks.

Although diesel fuel does deteriorate eventually, the main reason people recommend getting fuel at a high-volume dealer is that there’s less chance of getting water in the tanks. Tanks that sit partly empty are subject to condensation and busy dealers usually check the bottom of the tanks more frequently and refill them more often. Water mixes more readily with diesel than with gasoline and creates havoc if it gets in the injectors.

As for the oversize tanks, they are a convenience, but there are tradeoffs. Besides the initial cost, you’ll lose bed space and, of course, add weight. To estimate the added weight in pounds, multiply the number of gallons capacity by six and then add the tank’s empty weight.

– K.F.

Diesel Fuel Filling

Some years ago we used to own a 1984 Ford F-350 with the 6.9-liter diesel engine. It was a good truck, although a bit short on power, and we got good service from it. The worst part of owning the truck was filling it with fuel. It seemed no matter how hard I tried, it always foamed up and shut off the nozzle way too early, so I’d always have to stand there and manually babysit the nozzle until the tank was full. That was a pain, to say the least.

I’m looking at a new truck again, a Ford probably, and I was wondering if fueling is the same kind of problem these days. Have there been any improvements since those early days? I like the specs for the new Power Stroke diesel, but if I have to go through that same song and dance with filling, I’ll just buy the V-10 gas engine and be saved the hassle. Do you have any insight about this?

– C.S., New Era, Oregon

A I’m delighted to report that things have indeed improved greatly in the tank-filling fuel-flow department. We’ve driven numerous late-model Ford trucks with the Power Stroke diesel, both conventional F-series pickups and rigs based on the Super Duty cab and chassis with aftermarket beds, plus we completed a cross-country trip in a diesel-powered 2000-model Excursion. These rigs display remarkably forgiving fuel-flow characteristics with much less foaming and back splashing than in the old days.

We were particularly impressed with the Excursion. We had a couple dozen occasions to fill up, including several at commercial-type truck pumps. Even the high-flow nozzles set on their lowest fill point, which is still a high-flow rate compared to an auto-style diesel nozzle, successfully fueled the Excursion with no problems. Whatever the Ford guys did when designing the Excursion fill system was done right.

Today’s Dodge and GM diesel-powered trucks, likewise, are easier to fill than the older-vintage diesel-powered models.

The situation has also improved at the filling stations. First, there are a lot more stations selling diesel nowadays. Most of them that sell diesel also have a designated auto-diesel pump with the smaller-diameter, lower-flow-rate nozzle that is better suited to the average light-truck-type vehicle. An excellent traveler’s information source for stations that sell diesel is The Exit Authority, available from Interstate America, 5695 Oakbrook Parkway, Suite G, Norcross, Georgia 30093; (800) 494-5566.

– J.J.

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