Cold Weather Fuel Issues: The Safe Answer is Gelling

Nov. 17, 2014

In the coming months we will possibly see temperatures as low as we experienced last year. Fridged temperatures will send many fleets into a frenzy, and fuel gelling will be used to support many excuses.

The temperature is cold outside, below zero, say -2 or -3 degrees. The truck will not run, nor will it start, so we blame anything that may be on the dart board. The little ring in the center of the board is proper fuel maintenance and experience. Working outwards, the first ring is the driver, the next is maintenance, then temperature, and finally the granddaddy of all, the GELLING ring. Fuel gelling.

I have asked many people if they’ve seen gelling. They all say, “Yes.”  I ask, “When?”  The answer is always, “Well THEY said so.” I ask, “Who is ‘Mr. They’?” I have not as of this day met “Mr. They.”

True story

I got a call from a client’s veteran employee who told me that all their fuel was gelling and the pumps would not work.  I asked the normal questions, and all I got were foggy answers, or better yet frozen ones as it was zero degrees. I told him that it was not cold enough to gel the fuel, but he insisted it was and said they’d had to change filters on the pumps. He then told me that he’d climbed on top the 12,000 gallon above ground  tanks and looked inside the tanks and all the fuel was gelled.

Oh boy….now I was totally confused. We’d been blending with 30% KERO for a week and it was not cold enough to gel. For a slight moment I thought that maybe the fuel supplier had delivered straight  diesel, but the temperature was still not cold enough to gel even unblended fuel.  As a check,  we keep jugs of fuel outside for visual checks.

So what to do? I asked a member of the team to take a one hour ride on Saturday and see for himself. I thought we might need an emergency load of kerosene brought in, but with no room in the tanks that are “all gelled,” I was still searching for plans B, C or D.

Well it turns out that the snow plow guy hit the electrical box and shut down the pumps. How do you make the leap from an electrical box destruction to gelling?

The point is that gelling is the first thing blamed when there’s a fuel problem in cold weather. But it has to be below -15 degrees before fuel even begins to gel. What happens is that ice crystals build up in the fuel line’s 90 degree nipples, or on the filter water absorbent paper. The next stage is that the ice crystals melt by the time someone looks inside the filter, but they leave behind some wax build up.  It is not gelling as most describe the problem.


Here’s what’s really happening. First ice crystals form from condensation (think of an ice cold glass of beer on a hot summer day). Next paraffin wax drops out of the fuel.  Only then , last and if at all, do you get gelling.   The filters are where most of this happens, especially after a cold weekend when the trucks have not run enough to send warm return fuel from the engine to warm the fuel in the tanks. 

All of this can be attributed to poor maintenance of the vehicle, storage tanks and truck fuel tanks, as well as a poor understanding of fuel and poor communication with your fuel supplier.  Some believe everything can be solved with pour depressants and additives.  But actually there is a point you need kerosene. And if you’re buying fuel at a truck stop, it may be treated with additives, but in most cases not blended.   Kerosene is expensive and most truck stops choose not to blend because fleets do not want to pay for “fuel insurance.”

People way up in the northern US and Canada do not have any issues with fuel.  They have figured our how to maintain their fuel below ground, above ground and most important on the ground.  And you’ll see plenty of signs for KERO. What a surprise.

So when gelling is blamed for an engine that’s quit running, you better dig.  It is rare that that happens.  Sludge, crap, wax, water, amebas and asphaltines are not gelling. The filters are plugging because they’re doing their job, filtering.

Good asset management requires a deeper understanding of the problem and clearer explanation to solve it.

About the Author

Darry Stuart | President

Darry Stuart has more than 45 years of experience in the transportation industry. As President/ CEO of DWS Fleet Management Services, he has been providing “Limited Time Executive" services in transportation and fleet equipment management to a variety of companies.

An ASE-certified master technician, Stuart began his career on the shop floor before moving on to fleet management executive positions at Perdue Chicken, BFI (Browning-Ferris Industries), United Truck Leasing, the  Keen  Companies, and Cumberland Farms/Gulf Oil.

For 35 years, Stuart has been an active member of the Technology & Maintenance Council (TMC) of the American Trucking Assns., serving as the group’s general chairman from 2007-2008. He is the recipient of numerous industry awards, including TMC's Silver Spark Plug, which is given in recognition of an individual's outstanding contributions to the cause of excellence in heavy-duty vehicle maintenance management. He has been cited as an industry expert or authored over  250 articles on equipment and fleet management topics.

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