Oil Change: Improving Fuel Efficiency And Engine Performance

Changing your car's oil can have a positive impact on its fuel efficiency. Engine oil has lubricating properties that determine how efficiently your car runs. As engine oil ages, it breaks down and becomes less effective, and over time, heat damages the molecules in the oil that govern things like viscosity and lubricating ability. This causes the engine to run hotter and less efficiently, which negatively affects gas mileage. By changing your oil at the recommended interval, usually every 3,000 to 7,000 miles, you can avoid these efficiency-robbing conditions and improve your car's fuel efficiency.

Engine oil breakdown

Heat and Thermal Breakdown

One of the primary causes of engine oil breakdown is heat. As the engine heats up, it can cause a chemical reaction in the motor oil, leading to a change in its viscosity. This is known as thermal breakdown. The viscosity of engine oil, or its "weight," is crucial as it ensures the oil flows smoothly while coating metal engine components, preventing metal-on-metal contact. When the viscosity changes due to thermal breakdown, it results in decreased oil flow, increased oil consumption, deposit buildup, and potential damage to the engine's metal surfaces.

The sensitivity of engine oil to temperature changes varies depending on its composition. Petroleum-based motor oils are highly sensitive to temperature fluctuations, and the less refined the oil, the more susceptible it is to thermal breakdown. Synthetic oils, on the other hand, are engineered to withstand a broader temperature range and are much more resistant to thermal breakdown.

Oxidation

Oxidation is another common cause of engine oil breakdown. It occurs when the oil molecules react with oxygen present in the engine, leading to the formation of various chemical species, including aldehydes, ketones, hydroperoxides, and carboxylic acids. The rate of oxidation increases with temperature, and synthetic oils are often required in high-temperature applications to prevent rapid oil oxidation.

Sludge and Scaling

As engine oil ages and breaks down, it can leave deposits on the interior surfaces of the engine, known as "sludge" or "scaling." These deposits interfere with the proper flow of oil by blocking passageways and coating surfaces. This can lead to insufficient lubrication of engine components and reduced heat transfer away from the engine, negatively impacting fuel efficiency and potentially reducing the service life of the engine.

Additive Depletion

Thermal breakdown also causes the oil's additives to dissipate or wear out more quickly. Additives are crucial in enhancing or suppressing certain properties of the base oil. When additives deplete, it can lead to the formation and release of gases, acids, and other harmful insoluble compounds that can damage the engine as they circulate through it.

Base Oil Degradation

Base oil degradation is another factor in engine oil breakdown. The base oil can undergo physical and chemical changes due to thermal or compressive heating, oxidation, or other factors specific to the type of base oil used. These changes can impact the lubricating properties and overall performance of the engine oil.

Maintenance and Prevention

To prevent engine oil breakdown and maintain optimal engine performance and fuel efficiency, regular oil changes are essential. It is recommended to change engine oil at the intervals specified by the vehicle manufacturer, typically every 3,000 to 7,000 miles. Additionally, using high-quality oils, such as synthetic oils, can provide better resistance to temperature-induced changes and thermal breakdown.

Deposits on the engine's interior surfaces

Engine deposits, also known as "carbon deposits", are the gunk and grime that collect on the internal surfaces of an engine, including the valves, fuel injectors, and combustion chamber walls. These deposits are formed by the incomplete combustion of fuel, which leaves behind a black residue that builds up over time. This residue, consisting of unburned fuel and carbon, sticks to the internal engine surfaces.

As engine oil ages, it breaks down and becomes less effective at lubricating and protecting the engine. This breakdown is due to heat damage to the molecules that govern viscosity and lubricating ability. When oil loses its viscosity, it can't properly cushion and protect engine parts, leading to increased friction and reduced fuel efficiency.

Once oil breaks down, it also starts to leave deposits on the interior surfaces of the engine. These deposits, known as "sludge" or "scaling", interfere with the proper flow of oil by blocking passageways and coating surfaces. This can lead to insufficient lubrication of critical engine components, causing them to run hotter and increasing engine stress. Sludge and scaling also reduce the transfer of heat away from the engine, further impacting fuel efficiency and potentially reducing the service life of the motor.

The formation of engine deposits is a slow process, and removing them can be challenging. Disassembling, cleaning, and reassembling an engine is a complex and costly task. However, there are chemical cleaners available that can help dissolve and remove these deposits. Regular oil changes and maintenance can also help prevent the buildup of engine deposits and maintain optimal engine performance.

By addressing engine deposits and maintaining proper oil change intervals, you can improve fuel efficiency, restore engine performance, and extend the lifespan of your vehicle.

Under-inflated tires

The U.S. Department of Energy has found that keeping your tires at the recommended pressure can improve your gas mileage by up to 3%. This can lead to significant savings, especially when gas prices are high. For example, with gas prices at $4.00 per gallon, you could save $2.40 every time you fill up a 20-gallon tank. If you fill up once per week, that's almost $125 saved in a year.

To maintain optimal fuel efficiency and safety, it's important to keep your tires inflated to the recommended pressure. This information can usually be found on a sticker in the driver's side door jamb or in your owner's manual. Use a tire gauge to measure the PSI, and add or release air as needed. Most gas stations offer free air for tire inflation.

In addition to proper tire inflation, other ways to improve fuel efficiency include:

• Using the correct grade of fuel for your vehicle
• Reducing warm-up time in freezing weather and cool-down time in the summer
• Avoiding heavy traffic and poor weather conditions
• Performing regular vehicle maintenance, such as oil changes and spark plug replacements
• Adopting fuel-efficient driving habits, such as accelerating lightly and using cruise control

Poor engine tune-up

One of the main benefits of regular engine tune-ups is improved performance. Over time, engine components experience wear and tear, and parts like spark plugs can become corroded. By performing tune-ups, these parts can be replaced or cleaned, restoring the engine's power and smooth operation. This reduces strain on the engine, leading to improved fuel efficiency.

Additionally, regular tune-ups help extend the life of the engine. They allow mechanics to identify and address potential issues before they escalate into more significant, costly problems. Routine inspections and replacements of small components can save you from unexpected repairs and improve overall fuel efficiency.

Moreover, engine tune-ups play a role in reducing emissions. Ensuring that the engine burns fuel efficiently not only reduces your vehicle's carbon footprint but also helps comply with emissions standards. A well-tuned engine optimises the fuel and air mixture, allowing for smoother combustion and reduced fuel consumption.

Finally, tune-ups are essential for maintaining the resale value of your vehicle. A well-maintained car with a documented service history is more likely to retain its value, which is crucial if you plan to sell or trade in your vehicle. Regular engine tune-ups not only improve performance and fuel efficiency but also demonstrate your commitment to proper maintenance, making your vehicle more attractive to potential buyers.

Fuel-injected car issues

Regular oil changes can improve fuel efficiency, and fuel-injected engines are no exception. Fuel-injected engines rely on a series of interconnected components, including the fuel filter, pump, and injectors, to ensure the engine receives the correct fuel-air mixture.

Engine Misfires

Dirty or malfunctioning fuel injectors can cause the engine to misfire, resulting in a sputtering sensation and vibrations throughout the car. This occurs when the delicate balance between fuel and air entering the engine is disrupted. In addition to the fuel injectors, other factors such as spark plugs or engine tune-up issues can also cause engine misfires.

Rough Idling

If your vehicle sputters and shakes when idle, it may be due to dirty fuel injectors. "Rough idling" is characterised by varying RPMs even when your foot is off the gas pedal. It can also lead to engine stalling, causing a sudden drop in RPMs and engine noise as if the car has run out of fuel.

Poor Fuel Efficiency

Well-maintained fuel injectors contribute to optimal fuel efficiency. If your fuel injectors are dirty or malfunctioning, you may experience a decrease in fuel efficiency. This can be caused by fuel leaking from the body of the injector or by supplying excessive fuel when the internal springs are damaged.

RPM Needle Fluctuations

Dirty fuel injectors can cause the RPM needle on your dashboard to move unpredictably, indicating changes in RPM when your car isn't switching gears.

Engine Failure to Start

In rare cases, issues with fuel injectors can lead to engine failure. This occurs when the fuel injectors fail to deliver the required amount of fuel to the cylinders, disrupting the crucial air-fuel ratio needed for combustion.

Check Engine Light

The check engine light on your dashboard may illuminate or flash, indicating a potential issue with the fuel injector. This could mean that the fuel injector is dirty or malfunctioning, supplying an insufficient or excessive amount of fuel to the engine, impacting both performance and fuel economy.

Fuel Leaks

Over time, heat and moisture can cause cracks in the rubber seals or the fuel injector itself, leading to fuel leaks. If you suspect a fuel leak, have a trained technician inspect your vehicle to identify and remedy the issue.

Frequently asked questions