For diesel cars, winter can be tough

Donald Stutzman checks the filter on a diesel truck in his shop south of Washington (Kalen McCain/The Union)

Stutzman checks on the coolant of a truck in his shop. While not diesel-specific, the routine check is important for cold-weather car care. (Kalen McCain/The Union)

A pair of diesel filters in Stutzman's shop. (Kalen McCain/The Union)

WASHINGTON — There are plenty of upsides to a diesel engine. The lack of a spark plug makes maintenance generally more affordable, and the added torque makes a diesel the engine of choice for many drivers.

One thing diesel is not known for, however, is winter. The fuel contains a small amount of paraffin wax, a material that improves the efficiency of the product. As temperatures drop, however, that wax can crystallize and present major problems.

“Once it gets cold enough, the wax starts to gel up,” said Donald Stutzman, owner of repair shop Sunset Diesel, out of Washington. “If you don’t have any fuel flow, you won’t have any fuel coming through the injectors and the engine won’t run.”

Fortunately, for the mind winter driver, solutions to winter’s diesel-related woes are abundant. As a rule of thumb, Stutzman said upkeep work was worth it, compared to the cost of fixing things after the fact.

“Maintenance is always cheaper than fixing it once the problem went too far,” he said. “If you get stranded out at the side of the road, you’re going to have a service fee for somebody to come out and get you, you’re going to be late … stranded on the side of the road with no heat. And most people charge more for labor to come out there.”

Fuel additives

Additives offer a common solution to diesel gel-ups. They work by “altering the crystals that form in fuel during cold weather,” according to one NAPA Know How Blog post, which said additives could change “the chemical properties of the fuel, enabling it to flow at temperatures well below zero.”

Users simply pour some into the fuel tank, and the chemicals carry things from there. The practice is popular because anyone can do it with no need for a mechanic whatsoever.

Not all additives are made equal, however. Stutzman recommends Stanadyne or Hot Shot's Secret brands.

“If you don’t have good lubrication, you’ll end up taking the high-pressure fuel pumps out, and that’s a $10-15,000 expense,” he said.

Changing fuel, and filters

Wax gets stuck on fuel filters in the cold. Stutzman recommends changing the filters out at the start and end of winter, or every 15-20,000 miles under any conditions.

“Once you do start to get a wax build up, it’s hard to get rid of that wax buildup,” he said. “It’ll start restricting your fuel and obviously fuel mileage will drop too, it’ll make the whole truck run harder, stress all the components out.”

On the other end of the equation, drivers can seek out higher-refinement diesel, which has less wax.

“Number one fuel is a lot lower on the wax content than number two diesel fuel,” Stutzman said. “That’ll help with gelling up a lot … they usually have it marked on the pumps, where you can see it.”

Plugging in, warming up

Stutzman highly recommends plugging in a block heater for diesel vehicles overnight. Doing so ensures they don’t fall to problematic temperatures in the first place.

"Most diesel vehicles come with it,“ he said. ”If they don’t have a cord on it, they usually have a heater in the block, you’ve just got to put a chord on it.“

Before driving away in the morning, Stutzman also recommends letting a diesel pickup run idle for at least 10 minutes, or until coolant and oil temperatures hit around 100 degrees.

“If you start your engine and drive down the road right away, the metals on the piston and the cylinders try to expand too quick, and they’ll actually in essence lock up your engine while it’s warming up,” he said. “If you let it warm up for 10 minutes or so, all the materials will heat up at the same time.”

While the advice is sometimes given to gas vehicle drivers, Stutzman said it was especially true for diesel trucks, which run by compressing fuel to explode, rather than sparking it.

"The piston that a gas engine runs isn’t as thick as what the diesel ones are, So they heat up a little quicker,“ he said. ”And if you let a diesel warm up, it that’ll thin the oil to where it oils the turbo and all the different components better, break down the resistance.“

Comments: Kalen.McCain@southeastiowaunion.com