Some contractors are recognizing the benefits of diesel mowers and adding them to their fleets.

Dillon Schlimme keeps his four-mower fleet up to date by purchasing a new machine every year. Two years ago, when his equipment dealer suggested he try out a diesel mower, Schlimme initially thought it was just an attempt to sell him more expensive equipment. But after only one day in the field, the owner of Dillon’s Lawn & Landscaping in Clinton, Minn., was sold on the mower’s power, performance and fuel efficiency. He has since added two more to his fleet and plans to eventually replace all his gas-powered mowers with diesel versions.

“After the first day of use I had already made the decision to purchase a diesel just from the fuel savings alone,” Schlimme says. “At that moment I knew we had to start upgrading all of our mowers to diesel.”

Schlimme is not alone when it comes to recognizing the benefits of diesel mowers versus their gas- or propane-powered counterparts.

Contractors say these benefits include fuel savings, less maintenance, increased power and quieter engines. Many operators are adding one or more diesel mowers to their fleets for both everyday and specialized uses.

“Fueling your fleet with diesel has many benefits over propane and gasoline,” says Brian Schoenthaler, marketing specialist for The Grasshopper Co. in Moundridge, Kan. “Fuel economy and power are the main reasons a diesel mower is a good option for landscape contractors who are concerned about managing their costs and increasing productivity. Diesel-powered mowers have also been proven to provide higher torque, be more durable and use less fuel, and are also surprisingly environmentally friendly.”

Schlimme says his crews use diesel mowers on every property for nine to 10 hours per day. He likes that the engines run smoothly and quietly, and he says his crews normally let them idle on the trailer from job to job, so they’re running and ready to go when they reach the next site.

Dillon’s Lawn & Landscaping, a $325,000 company, provides 60 percent maintenance services and 40 percent lawn care services to a 70-percent residential, 30-percent commercial clientele.

With many properties that contain hills and slopes, Schlimme says his diesel mowers can climb hills more easily than his gas units, especially when using a bagger. His diesel mowers also require less maintenance and fewer oil changes.

“We don’t have to worry about the carburetors gumming up and they run smooth and quiet,” Schlimme says. “I can run two weeks on an oil change, which is nice because there is less downtime for maintenance—and time is money.”

Schlimme says the fuel savings are by far the biggest advantage to operating his diesel mowers. On a typical day, his gas mowers use 9 to 12 gallons of gasoline depending on the conditions. His diesel machines use about 6 gallons of fuel per day, which results in huge savings by the end of the year.

Schoenthaler agrees the fuel savings can be significant, adding contractors who use “clean-diesel” mowers are seeing up to a 50-percent reduction in fuel usage compared to gasoline- or propane-powered mowers operating with the same horsepower. He says a diesel mower uses an average of 650 fewer gallons of fuel over the course of a 1,000-hour mowing season than its gasoline or propane counterparts because diesel mowers use fuel at or below one gallon per hour compared to gasoline and propane mowers, which consume between 1.65 and 1.85 gallons per hour.

“The biggest reason that diesel mowers are a good fit with a landscape company’s mower fleet is cost control,” Schoenthaler says. “By extrapolating those savings across a fleet, the fuel savings numbers become very attractive.”

Diesel mowers also can be easier on the environment. Schoenthaler says some mowers, such as the Grasshopper MaxTorque diesel engines, run on ultra-low-sulfur diesel No. 2, which emits less carbon dioxide, carbon monoxide and other toxins into the air per hour than gasoline or propane engines with the same horsepower rating.

“The diesel fuel of today is not your grandfather’s diesel,” he adds. “Gone are the days of black-smoke-belching diesel engines.”

Jeff Grizzle, owner of Grizzle Lawn Care in Wimauma, Fla., owns three diesel mowers and uses two of them to cut 60 to 70 lawns per day. The company’s third diesel mower, a 72-inch zero-turn, is used on larger lots or on lawns that are significantly overgrown. Grizzle says the power and speed of these mowers is a benefit when maintaining his clients’ large, rural properties covered in thick Bermudagrass. Grizzle Lawn Care provides primarily maintenance services to a residential clientele.

“One pro to using a diesel mower is definitely the power,” Grizzle says. “Our diesel zero-turn outperforms our gas units in thick, tall grass every time.”

While Grizzle sees benefits from the power of his diesel mowers, he says that level of power may not be necessary for all contractors.

“One question contractors need to ask themselves before buying a diesel-powered mower is, ‘Do I need a mower with this much power?’” he says. “If you’re only mowing a few well-groomed yards every day, there’s no point in spending the extra money on a diesel mower.”

With quieter engines and less vibration, diesel mowers also can be easier on crew members who operate them all day every day, says Tom Vachal, senior turf product manager for the Kubota Corp. in Grapevine, Texas. With a low center of gravity, diesel mowers can also be safer to operate on hills and uneven terrain, he adds.

“Overall operator fatigue is less with diesel mowers, which is a pretty big thing because your people are a large expense and taking care of them and keeping them around is important,” says Vachal. “If they are working on a big, comfortable machine that doesn’t wear them out, they are more apt to stay around.”

Grizzle and Schlimme agree the biggest downside to diesel mowers are the upfront costs. Schlimme says his diesel mowers cost several thousand dollars more than their gas counterparts. While Grizzle says his diesel mowers tend to break down less often than his gas versions, he says repairs tend to cost more. Schlimme says his has had some issues with the radiators getting clogged with grass and dirt, causing the mower to get hot. He says when the mower gets to a certain temperature it will shut off the blades so the operator knows to stop and clean it. Most diesel mowers also come with a hood over the motor which can make it harder to perform oil changes and other maintenance, he adds.

“So far I haven’t seen a brand that is easy to work on,” Schlimme says.

Schlimme says contractors should make sure they are logistically prepared to operate a diesel mower, and says for the first year it was a hassle to have one gas mower and one diesel mower on his truck at the same time.

“We have transport tanks in our trucks with gas, so the operator on the diesel mower had to always make sure he had a can of diesel with him to fill up if he needed it,” Schlimme says. “If I could do it over again, I would have just bit the bullet and bought two diesel mowers at the same time.”

Schlimme says contractors should consider how much time they spend mowing to make sure a diesel mower is worth the investment.

“We mow about 140 lawns per week, so each mower gets about a 1,000 hours per year,” he says. “If you don’t do that much mowing and only put a couple hundred hours a year on the mower, then a gas mower is more than likely a better choice.”

Vachal says contractors should also take into consideration how long they plan to own the equipment and should look at diesel machines as long-term investments to truly reap their benefits.

“We are seeing a growing number of contractors adding diesel products to their fleets every year,” he says. “Improved fuel efficiency and reduced operating expenses associated with the product seem to be key. If contractors are trying to move more money to the bottom line, diesel could be a good way to that.”

Photos: Top (Grasshopper), Middle (Kubota)