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Diesel Motor Vs Petrol Motor: Demolishing Myths

enero 11, 2023

Although there is a trend towards electric or hybrid cars in the market these days, they are still not that easy to get or become popular. Therefore, for many it remains the most important factor when deciding whether to choose a car with a diesel motor vs petrol motor.

According to experts, better fuel efficiency and longer engine life are some of the advantages of diesel engines in the automotive industry.

Comparison of Diesel Motor Vs Petrol Motor

Some interesting comparisons regarding diesel motor vs petrol motor are:


• On diesel engines, the fuel is compressed until the same pressure ignites it, starting the car.
• While on petrol engines, air enters the engine through the cylinders, and sparks from the spark plugs ignite the fuel to start the vehicle.


• Diesel engines provide more torque (the ease with which the engine moves the vehicle) even at low revs, reducing fuel consumption.
• Petrol engines need to burn more fuel to get more torque.

Oil change

• On diesel engines, oil changes must be done after approximately 20,000 kilometers.
• While on petrol engines oil change should be done after 10,000 kilometers.
First service
• For Diesel engines it must be done very quickly to avoid wear on rings and pistons. During the first 100 hours of use.
• On petrol engines a service should be done from the first 10,000 to 15,000 km.

Repairs and spare parts

• Diesel engines tend to need fewer repairs, but in contrast they are more expensive.
• Petrol engines require more repairs, and they are cheaper.


• Higher on diesel engines because electric starting is simpler, which reduces the risk of failure.
• Petrol engines have a shorter duration.


• Diesel engines are louder due to the knocking sound of diesel compression.
• Petrol engines are quieter in comparison.

Battery consumption

• Starting requires more power on diesel engines, and therefore consumes more power.
• Petrol engines use less battery power to start.


• Diesel engines require less power, and have more torque (measure of the force that is applied to a rod and that is used to make an object rotate)
• Petrol engines have more power but less torque

What Is AdBlue? Why Should It be Taken into Account?

It is a fact that in the diesel motor vs petrol motor discussion, the diesel one spends less than the gasoline option with the same power. This is not a myth; they are inherently more efficient engines because they have a higher compression ratio and fuel energy density.

But the statement that diesel is always cheaper to maintain is not true. Buying a diesel car is not a mathematical formula: have you considered maintenance or refilling AdBlue? What is DEF (Diesel Exhaust Fluid)?
AdBlue is the trade name for an aqueous solution of approx. 32.5% DEF. AdBlue is not toxic, but corrosive. We are not in any danger from handling it, but we must take certain precautions so that our bodies do not come into contact with it, and carefully clean up accidental spills.

In short, we’ve seen some low-emission engines that don’t require AdBlue systems, and so far they’ve far exceeded emissions standards using another catalytic converter that doesn’t require additives, the so-called NOx-Trap. In any case, any diesel of a certain power already needs AdBlue to overcome the strictest emission regulations.

AdBlue is essentially an additive and therefore requires a system for its use. This additive is not mixed with gasoline, but is integrated with other catalysts in the cylinder near the exhaust port, in emission reduction systems such as particulate filters. In this equipment, the AdBlue is crushed to achieve a chemical process in which the high-temperature gas causes the AdBlue to produce ammonia and decompose the NOx molecules into nitrogen and water, which is logically less harmful to health and the environment.

The only thing to know is that when the AdBlue tank runs out, the car goes into error mode and doesn’t even start the engine until AdBlue is refilled.

Do You Save More Because It Is Diesel? Is This True or Is It a Myth?

You’ve heard this phrase hundreds of times. Your friend announces that they have bought a new car: «I bought a diesel car because it consumes less». For years, diesel has been sold as a panacea for saving money. Most people think highly of a diesel car, at least for now, because it emits less CO2 than an equivalent gasoline engine.

They use less fuel, but many people forget or don’t realize the complexity of modern diesel engines. In many cases, they are not even ideal for their needs. If you think about it, they are probably much more expensive than gasoline cars, which can actually use two more liters per hundred kilometers.

Also, for some drivers, diesel may be the better option, especially if they use it primarily on the highway

When the difference between a diesel motor vs petrol motor is raised, we associate gasoline engines with very expensive engines. This used to be true. Gasoline engines use a very inefficient carburetion system and produce power based on displacement.

Twenty-five years ago, the standard 1.6-liter four-cylinder gasoline engine didn’t even make 100 horsepower.
Diesel engines at the time had very low pumping: despite having very little power, they had very low fuel consumption. The first turbo diesels barely exceeded 100 horsepower in their highest output versions.

Today, almost all modern gasoline engines are «downsizing»: very small displacement engines that, thanks to supercharging, and direct injection, produce power figures equivalent to larger engines with very low consumption.

Blocks with a volume of less than 1.5 liters often reach (or exceed) 150 hp with a real consumption of less than 7 liters/100 km. Even a high-performance engine with almost 300 hp can manage a fuel consumption of less than 9 liters/100 km.

Do You Know How to Maintain a Modern Turbo Diesel?

A modern turbo diesel engine is a very complex piece of equipment. Without going too deep into the mechanical differences between a diesel motor vs petrol motor, the components of a diesel engine are subjected to much higher internal pressure than those of an equivalent gasoline engine.

To produce 120 horsepower, the 1.6-liter diesel engine must use a high-pressure variable geometry turbocharger. Its Common Rail direct injection system works with very expensive piezo injectors at pressures up to 2000 bar.

In addition, their anti-pollution systems are extremely complex. This very advanced technology does its job, but it is not perfect, since it has ideal operating conditions. If the car revs too low, mechanical stress can cause long-term problems, filling the particulate filter with soot and clogging the EGR valve, which stops it working properly.

If we were to only operate for a short period of time, we would significantly reduce the life of your anti-pollution systems, as they require a constant minimum temperature to function properly.

This also implies maintenance, which must be rigorous, as well as more expensive modifications than gasoline engines. There are more mechanisms to check, oil is more expensive and new generation cars need to be filled with AdBlue.

A properly treated and maintained diesel engine is just as reliable as a gasoline engine. But if the opposite is true, or if seemingly simple maintenance, such as changing the fuel filter, is neglected, the potential for failure is high.

Diesel Motor Vs Petrol Motor: Think About What You Need Your Car For

There are diesel motor vs petrol motor calculators that will tell you how long it takes to pay off a diesel car, which is more expensive than a gasoline car. The problem is that they often don’t account for differences in maintenance costs, insurance costs, or potential damage. An expensive repair can unbalance the entire mathematical equation.
When considering the differences of a diesel motor vs petrol motor, remember that there are a number of factors to consider.

In some cases, diesel can be a good way to save money. If you run a lot of miles a year, especially on the highway, diesel will save you money and you won’t have the problems mentioned above.

How much is «many kilometers»? There is no magic number. But driving 20 kilometers a day to work or doing several 2000 kilometers a year is not «a lot of miles.» Not even 15,000 km a year is enough to justify the purchase.

There are other things to think about. Are you planning to drive your car for more than 300,000 km? Do you plan to drive the same car for 20 years or do you want something different after 8 years? Will your transportation needs change? Can your car last 15 years without major problems?.

These questions affect diesel motor vs petrol motor math formulas, so they should not be taken literally

With all this in mind, there is one more thing to consider. Cities will soon face pollution restrictions. These restrictions may require the phasing out of diesel vehicles from major urban centers. If at some point it is decided to link road taxes to emissions of nitrogen oxides or particles, diesel will not be a benefit either.

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