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The Brrr factor
With ULSD in widespread use and the popularity of biodiesel growing, truckers need to know about special winter concerns

By Jeff Barker
contributing writer

The introduction of ultra-low sulfur diesel and biodiesel fuels into the trucking industry has presented us with many challenges in recent months – from our engines running hotter and getting reduced fuel mileage, to prematurely clogged fuel filters, just to name a few.

Pretty aggravatin’, isn’t it?

As it is, a few of us may have made the mistake of not being prepared to operate our trucks in brutally cold weather, only to learn the hard way when our engines sputtered and wouldn’t restart because the fuel in our tanks gelled up. Trust me, as a lifelong resident of south Texas who knew nothing about fuel gelling in cold weather – I had to learn about it the hard way several years ago.

Unfortunately, with winter temperatures upon us, we have even more real-world challenges to face with our new-age fuels that were not quite as prevalent with the low-sulfur diesel that we have been using since its introduction in 1993.

Not so long ago, many of us were used to mixing kerosene in our diesel to help lower the gel point.

However, with the new 2007 engines here, we need to acknowledge that it’s a new ballgame when it comes to both preventing fuel gelling and dealing with a gel-up should it take place.

Gel points
As temperatures drop, truckers need to be more aware of the ambient temperature. Some of the new-age diesel will have a higher gel point than the diesel we have been using for a while now, so it’s very important that anyone who owns and/or operates a truck be well-versed on what to do.

A thermometer in the cab to measure outside temperatures will be your new best friend. Keeping an eye on weather forecasts will help you avoid potential problems as well.

Biodiesel fuel can start clouding up at temperatures between 30 and 50 degrees depending on the blend. Straight ULSD fuel may begin to gel up at temperatures between 20 and 32 degrees.

However, No. 1 ULSD, also called ULSD K because of the kerosene content, decreases the gel point for cold weather driving.

By comparison, the old untreated low-sulfur diesel was usually stable in temperatures down to zero degrees. With that in mind, we will be required to take action much sooner – or learn a thing or two about that brrrr factor the hard way.

The idea is to treat the fuel, keep it warm throughout the fuel system, and be fanatical about keeping the water content as low as possible.

Water-fuel separators
Most late-model trucks come factory-equipped with fuel-water separators. Be sure your truck is equipped with one. If it’s not, get one and install it as soon as possible. Get in the habit of draining the water out of it every time you stop and fuel the truck. Refer to its instructions and stay in compliance with EPA regs.

Wrap those lines
Unprotected fuel lines are one of the easiest places for the cold to cause gelling. Wrapping your fuel lines with a non-flammable thermal barrier material will help the fuel stay warm.

Those with some ingenuity can make a removable, reusable cover that attaches to their fuel filters while they’re mounted in place.

This material can be purchased at hardware stores, or automotive “speed shops” that sell it for use on race cars.

Fuel additives
When it starts getting cold, fuel additives tend to start flying off the shelves. Reputable fuel additive manufacturers are aware of the development of the new ULSD and biodiesel fuels, and have made sure their products are compatible with them.

Depending on how much you travel in cold weather, use your better judgment in determining how many bottles of fuel additives you need to carry. I’m not going to recommend buying a whole pallet with 50 cases of fuel additives and strapping it down on the catwalk behind your sleeper, but do yourself a favor and have a few bottles on hand.

If your engine is still under warranty, do your research and make sure the use of additives will not
void it.

A word of caution about storing fuel additives: Do not store them in your cab, sleeper or even in your side boxes under your bed. If one of the bottles were to develop a leak, inhaling the toxic fumes could be hazardous. Store them in a well-ventilated place outside of your cab.

Winter blends
Making a few phone calls to truck stops on your route and asking questions about the availability of these winter blends will help you be prepared.

To lower the gel point of your fuel, either put a few gallons of ULSD K or No. 1 ULSD – which is the same thing – in each tank. Or if traveling in extreme temperatures, mix it at a 50 percent ratio.

Mechanical engines
Mechanical engines don’t send as much hot return fuel to the fuel tanks as the newer electronic engines do. Consequently, the possibility of gelling is greater in them. Installing fuel tank heaters would be a good idea.

Know when to shut down
While there are anti-idling laws in place in most states, there are usually allowances in place for it to be legal to idle in temperature extremes.

Setting your engine’s idle speed at around 1,000 rpm will help increase fuel circulation in the system, thus increasing the amount of hot return fuel being sent from the engine back to the fuel tanks, especially on electronic engines.

APU use
Many of us like the idea of saving fuel and not idling as much with an APU on board, but unfortunately those little engines can’t send enough hot return fuel back to the tanks to prevent gelling.

In that case, you may have to accept the fact that your truck engine will need to idle while it’s extremely cold. I’ve made the mistake of becoming too reliant on an APU in the past. I had to wake up at 3 a.m. once and figure out how to thaw out my fuel before I could get my truck engine to start. It’s sure as hell not fun, I’m telling you.

Thawing out
If you’re stuck on the side of the highway and your truck won’t start, try putting a bottle of emergency fuel treatment in each tank, wait 20 minutes, and see if it will start.

If not, prepare to call for an expensive road service and possibly a tow truck to come out to move your truck to the inside of a warm building to let it thaw out.

If you managed to get the engine to run for a bit before it died again, replace the fuel filter, as it may be clogged with paraffin wax. Keep doing this until you know all of the wax is out of the fuel system.

Be safe out there this winter.

Jeff Barker is an OOIDA member and a former certified diesel mechanic. He may be reached at

Editor’s note: This article is for information purposes only. If you’re not sure about performing the work yourself, it’s advisable to seek the help of a competent professional.