25 Myths About Diesel Engines That Simply Aren't True

When cars debuted onto the market, some people questioned how cars functioned while others were satisfied with driving a vehicle and not knowing the mechanics. The first car produced had a gasoline engine and worked, so most people didn't bother with questioning the status quo.

As with all inventions, a few people want to scrutinize it to see the potential it has and how they can modify it to make it better. One of the people who believed that cars could operate better than if they had a gasoline engine was Rudolph Diesel.

He was a German inventor and a mechanical engineer, responsible for the invention of the diesel engine. The invention is a combustion engine, and the elevated temperature of the air in the cylinder due to mechanical compression causes the ignition of the fuel. A diesel engine has the highest thermal efficiency of any internal or external combustion engine due to the high expansion ratio, enabling heat dissipation by the excess of air.

Diesel engines account for half the engine sales in Europe, and its sales have increased in the U.S. since the 1970s. Considering that diesel engines have been around for more than a century, many people have formed beliefs about the engine that just aren't true. We wanted to debunk the myths to educate consumers, so we compiled a list of myths that most people believe about diesel engines that are incorrect.

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25 Diesel Is The Largest Cause Of Air Pollution

via Motoring Research

Diesel engines have come under fire for emitting a tremendous amount of air pollution, but studies have revealed that diesel engines don't cause as much pollution as some car experts claim.

The Guardian reported that chief executive of Society of Motor Manufacturers and Traders, Mike Haws stated, "Today’s diesel engines are the cleanest ever, and the culmination of billions of pounds of investment by manufacturers to improve air quality ... The allegations against diesel cars made in recent months threaten to misguide policy making and undermine public confidence in diesel. It’s time to put the record straight.”

24 Diesel Means Loud And Dirty

via Truck Trend

The sale of diesel engines have increased, but many consumers still believe the engines are rattle boxes that emit large amounts of smoke. The older direct injection diesel engines were more audible than newer ones.

Common-rail technology made diesel engines almost as quiet as gas engines. When the EPA put its foot down, car manufacturers were forced to make diesel engines cleaner to sell the vehicles in the U.S. legally. These days, diesel engines emit less NOx due to exhaust gas recirculation.

23 Propane Is Like Nitrous For Diesel

via KGWN

Many hot rodders believe this myth to be true. The funniest part is that most of them don't own diesel engines. Propane in an engine is like burning another fuel, and nitrous is the equivalent of fitting another turbo. Propane injection improves fuel economy and provides a small hitch in power.

The best use for it is in unmodified engines. Propane can cause engine damage, as drivers have no control over its ignition point. Most people use nitrous for competition, as it adds horsepower to the engine.

22 Idling The Engine Doesn't Waste Fuel

via Grist

Really? You might not empty an entire tank if you idle, but you will waste fuel on a diesel engine if you idle it. Studies have indicated that idling your vehicle for an hour results in wasting one gallon of diesel fuel. That leads to less time you spend on the road and more time filling the tank.

The studies also indicated that drivers had wasted more than $2 billion on unnecessary idling, according to Burnsville Volkswagen. If you want to incur less fuel costs, don't idle your diesel engine.

21 Finding Diesel At The Pump Is Impossible

via TMC Financing

Considering that diesel-powered trucks and cars have garnered a lot of popularity, the market has taken an interest in diesel engines, as it wants to provide consumers with what they seek. Most gas stations offer diesel, as competition has forced them to offer it.

Most diesel drivers stated that they didn't incur any difficulties finding diesel at any pump, though they have been driving for years. Since consumers demanded diesel engines, evidenced by the sales, the market will provide.

20 The Fuel Is More Expensive Than Gasoline

via The Berkshire Eagle

We agree with you if you say diesel is more expensive than gasoline in Chicago-land, but the rest of U.S. offers diesel at the same price as gasoline or lower. Illinois taxes diesel at higher rates than gasoline. A fuel expert explained that the cost of producing diesel is not more than gasoline; it is the local tax structure that influences the price.

In other parts of the world such as South Africa, diesel is cheaper than gasoline throughout the entire country. The price of diesel depends on where you live.

19 Diesel Vehicles Are Good Only For Towing

via Caravan and Motorhome on tour

Although this myth might have been true in the past, the modern engines are comparable and efficient. The reason that many consumers have associated diesel vehicles with towing is that the engine produces more torque at low engine speeds with a flatter torque curve than a gasoline engine.

Volkswagen has concentrated on making fuel-efficient diesel-powered cars that can provide more than 40 mpg on the highway, as well as 30 mpg in the city, according to Nitro Nine. Europe has recognized the effectiveness of diesel engines, which is the reason it has many diesel engine cars on its roads.

18 Diesel Is Expensive To Maintain And Repair

via Youtube

Not any more expensive than gasoline engines. High diesel prices and stringent emissions have contributed to consumers believing that a diesel engine is a more expensive option. When consumers purchase cars, the most important aspect they look at is the durability of the vehicle.

Diesel's main benefit is the longevity that it has provided to its owners. Drivers who maintain their diesel engines will rarely experience failures and will get better fuel economy than its gasoline counterparts.

17 Diesel Gets 20 MPG + While Towing

via The Fast Lane Truck

Think about it. If a diesel engine could give you 20 mpg without a trailer, then it will provide less while towing due to the added weight. The more realistic figures are 15 or 16 mpg while towing.

This myth has given diesel engines a bad reputation, as many consumers buy diesel hoping to get 20 mpg or more while towing and are disappointed to find out when the vehicle doesn't reach those figures. Don't be fooled by whatever is advertised, stick to the figures and facts.

16 Diesel Doesn't Start Easy In Winter

via Hard Working Trucks

Gasoline engines also struggle in cold conditions, as much as some diesel engines. That myth creates a perception that all diesel engines will give you countless problems in winter. Most diesel vehicles have block heaters. Some diesel owners don't know about the block heaters or don't know how to use it, but car experts recommend the use.

One of the key ways to ensure that older diesel engines start in cold conditions is by checking that the intake grid heater is functioning, the batteries are healthy and glow plugs are up to scratch.

15 A Laggy Turbo Is Good

via Auto Car Modification

Big, single turbochargers can provide great performance, but a small turbo is better for the kind of driving that regular drivers engage in: commuting or towing. A big, single turbocharged engine will suck you into the seat, but at low rpm, the driver compromises some of the torque needed to move heavy loads, according to Truck Trend.

In overdrive, the driver risks surging or damaging the turbo. We should also note that large variable-geometry turbos don't always hamper driveability.

14 Biodiesels And Vegetable Oils Are The Same

via Biodiesel Magazine

While many people think this is true because that's what others have told them to believe, the truth is that these two aren't the same. Drivers shouldn't run a straight mix of biodiesel or vegetable oils through a factory fuel system. Less than 20% of diesel blend is present in diesel fuel at gas pumps.

Although one can make biodiesel from vegetable oil and animal fats, it can come from natural minerals such as algae, sunflower, and soy. Vegetable oil requires an upgraded lift pump due to the thick viscosity.

13  You Can't Tune A Diesel Engine

via Youtube

Yes, you can. Drivers who want more power and torque from their diesel car will be delighted to know that you can tune a diesel engine. The truth is that diesel engines have withstood better tuning than gasoline engines.

One of the aspects that prove you can tune a diesel is that diesel engines have adjustable components that need a periodic setting for longevity and economy. Drivers who want optimum tuning of gasoline engines will have to add extra components.

12 The Manufacturer Doesn't Have A Turbocharged Model

via Driving Line

Car manufacturers have noticed the significant difference between diesel and gasoline engines, prompting the companies to manufacturer diesel engines. Most automakers manufactured diesel engines since 1984 and designed the engines while keeping turbocharging in mind.

In some countries, the cars are turbo fitted at the factory. Keystone reinforced top piston rings, oil to water engine oil cooling and auxiliary oil coolers are standard build and fitment in Toyota, Ford, Mazda, Nissan, and Mitsubishi.

11 Water Cooling Is Unnecessary In Diesel Engines

via Your Mechanic

If you want your diesel engine to blow up, then don't worry about the water cooling. Drivers who expect longevity from diesel engines will take water cooling seriously, as it is necessary for any conversion to maintain engine oil temperatures to factory specifications.

Adding the turbocharger means that you're using the oil supply for lubrication. The result is the creation of heat transfer into the engine oil, requiring additional cooling. The benefit of water cooling is that it eliminates the need to idle-down.

10 You Shouldn't Boost The Factory Non-Turbo Engine More Than 5 To 7 Lbs Per Square Inch

via Stance is Everything

Wrong again. Manufacturers have built high-speed diesel engines with strong bottom ends, incorporated for Turbocharging. Less air and more heat are the results of a low boost on a diesel engine. By boosting the pressure from 8 to 12 lbs, it means that there is more air and less heat.

You should set your system to run air rich and override the fuel delivered, creating a reduction of piston crown temperatures. That means, the harder you push the vehicle, the more it cools.

9 You Must Idle The Engine In The Morning

via NJ

That might have been true in the good old days, but technology has changed the way we live. The advancement of engine technology has eliminated the need for drivers to idle their diesel engines in the morning. Most engine manufacturers recommend that you should not idle for more than three minutes before driving modern diesel engines.

Idling leads to doubling the wear on the vehicle than driving on a highway. The additional damage results in exorbitant maintenance expenses and reduced engine life.

8  Correction Factors For Gas And Diesel Engines Are The Same

via Your Mechanic

The reason that this myth is false is due to most diesel engines being turbocharged. Turbochargers provide a boost while correction factors show how much power a vehicle would produce at sea level.

According to Truck Trend, correction factors are lower for turbocharged engines than for non-turbo versions. Also, the higher the boost, the lower the correction factor. Don't believe that correction factors for gas and diesel engines are the same, as it's not true.

7 Diesel Cars Don't Perform Well

via Truck Trend

Diesel engines are common in trucks; therefore, many people believe that diesel engines provide poor performance. You need to take the weight difference between a truck and a car into account when making that comparison. Many diesel drivers believe that the cars perform better than gasoline engines.

The reason that diesel drivers state that is due to diesel engines providing the best power when the engine's revolutions per minute are low. That happens mostly at speeds below 65 mph.

6  Governments Are Clamping Down On Diesel Engines

via Agencija DAN

This myth is related to other myths such as diesel engines causing a lot of air pollution and noise. The myth is true to an extent. So, to what extent? The older diesel engines have emitted a lot of pollution, but technology changed that. When the government raised its concerns about diesel engines polluting the air, automakers used technology to advance diesel engines, making it cleaner and efficient.

The modern diesel engines comply with government standards, so consumers thinking about buying a diesel engine car don't have to worry.

5 The Engine Performs Poorly At High Elevations

via Mountain Chevrolet

The truth is that diesel-powered engines perform better than gasoline engines at higher elevations. The reason for the better performance is that the air is thinner at higher elevations; hence, gasoline engines don't need to add a lot of fuel to maintain the air ratio, affecting the performance.

Since a diesel runs lean, the additional air in the combustion chamber allows the driver to add more fuel, providing you with more power than a gasoline engine. A diesel engine will allow you to charge up the hill while other engine alternatives suffer.

4 Diesel Engines Provide Poor Fuel Economy

via Mental Floss

In some countries, diesel engines have garnered a reputation for providing poor fuel economy. Although the stigma might be there, it doesn't mean that the statement is correct. The truth is that a diesel cycle has a higher thermal efficiency than the Otto cycle, principles that describe internal combustion engines using gasoline.

The other fact is that diesel fuel has a greater energy content per volumetric unit than gasoline, contributing to greater fuel economy. So, diesel engines have greater thermal efficiency and more energy of gallon per fuel, according to Diesel Hub.

3 The Engines Aren't Good For Long Trips

via Climate Action

One of the reasons that this myth might have been started is due to the lower presence of diesel engines than gasoline engines on the road. Some consumers also believe that diesel engines don't adjust to different environments as well as gasoline engines.

The truth is that diesel engines perform better than gasoline engines in a variety of conditions. A diesel engine will most likely provide you better performance on long trips than gasoline engines, especially if your journey involves high altitudes.

2 Today's Diesel Engines Are The Same As Years Ago

via Youtube

A number of reasons exist why that isn't true. Firstly, technology has changed in the last few decades, which has impacted the performance of diesel engines. Common-rail technology has improved the diesel engine by making it quieter and emitting less smoke.

Since Congress passed Phase 2 of the Corporate Average Fuel Economy and emission control guidelines, manufacturers had to make significant changes to the production of diesel engines. Diesel engines have come a long way since Rudolph Diesel invented it in the late 1800s.

1 The Choice Of Fuel Has No Impact On Exhaust After Treatment

via Car Magazine

Many fleet operators believed that the control of their exhaust after treatment isn't within their control. Marketing Director of Refined Fuels for CHS, Ron Jessen said, "It may surprise fleet owners to learn that using a high-quality or premium fuel like Cenex Roadmaster XL can actually lead to even cleaner emissions."

That is because of the gas recirculation valve, the selective catalytic reducer and diesel particular filter that work together to scrub the exhaust. "A good detergent package and a high cetane level will help filters stay cleaner longer," Jessen said.

Sources - Truck Trend, Fleet Owner & The Guardian

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