How often should you change engine oil?

Engine oil performs several functions in a car, including lubricating engine components, reducing friction, and minimizing unnecessary loss of power.

Keeping your engine well lubricated will keep it in good working order and reduce the possibility of unexpected failure. While changing your engine oil is relatively easy, our guide will help you understand how often you should change the engine oil, and what type of oil is best for your vehicle.

What influences oil change frequency?

Car makers set different car maintenance schedules for engine oil changes based on engine types, configurations, and regional factors like fuel octane rating and quality.

Generally, they want you to stretch out the engine oil change to 10,000 to 20,000 miles, which, in theory, helps you reduce car maintenance cost and visits to the dealerships, but it’s just wishful thinking.

Carmakers base their default oil change recommendations on lab-tested scenarios, simulating driving on highways and other areas with minimal loads. Any adjustment to this scenario leads to a corresponding change in the oil change interval and prompts you to adjust it according to your own driving scenario.

In reality, how often you should change your oil mostly depends on:

• Driving conditions and habits
• Oil-life monitor readings
• Vehicle age

Driving conditions and habits

Vehicle owners often base oil change frequency on the average miles driven per year. It is a very sensible and logical approach, but the yearly vehicle mileage is just one of a few factors helping to determine when to change your engine fluids.

First, it's crucial to analyze the environment and conditions in which you will drive the car. For instance, in mixed conditions with at least several longer drives in one month, it is advisable to change the oil at least every 7,000 to 8,000 miles or once a year – whichever comes first.

For numerous short trips where your car's engine rarely reaches working temperatures, you should consider changing the oil between 4,000 and 5,000 miles before you start to hear unusual noises from your engine.

In this scenario, the engine oil will accumulate a significant amount of unburned fuel and condensation, leading to degradation. Under these conditions, engine oil loses its valuable lubricating properties, requiring more frequent oil changes.

Stop-and-go traffic, dusty environments, or long periods in temperatures below zero also necessitate more frequent oil changes.

Oil-life monitor readings

Many modern cars have a handy tool – a built-in oil-life monitoring system, which is far more helpful than traditional car dashboard warning lights, which illuminate based on the manufacturer's default algorithm.

The oil-life monitoring system calculates parameters such as mileage, engine idle time, engine temperatures, trip times, engine loads, and starts and stops. It then provides an estimated reading of the oil's remaining life, and if needed, the system will automatically display a notification when your car maintenance is due.

Vehicle age

Oil change for older vehicles could be difficult, given that this term refers to a broad range of cars that vary significantly in every possible aspect.

Until the 1980's, cars did not have sophisticated electronics, which could, for example, prompt a maintenance required light or any other warning. As a result, owners primarily followed the yearly mileage schedule.

While you might assume that advancements in engine oil innovations would bring oil changes for older cars on par with modern vehicles, it's wiser to schedule engine oil changes based on the production date:

• Cars built since 1990. Even by today's standards, these vehicles are considered relatively modern, allowing owners to safely extend the interval for oil changes between 6,000 and 8,000 miles.
• Cars built since 1970. Classic car owners generally suggest changing the oil every 4,000 to 6,000 miles.
• Cars manufactured before 1970. Cars made until the 1970s are quite delicate. It means an oil change should be done every 6 to 12 months or every 3,000 miles.

Why is changing the oil important?

Numerous moving elements in engines need to be properly maintained in order to prevent damage.

Important engine components eventually become polluted with dirt and other particles over time. To eliminate the extra filth that accumulates in the engine, replacing the oil after a set period of time is crucial.

If the longevity of your car’s engine is a top priority, the following reasons should be enough to convince you to change the oil on time.

• An oil change improves fuel economy. Oil and dirt buildup inside the engine makes it work harder to generate power, consuming more fuel. Appropriate maintenance reduces unnecessary strain on your engine, extending its life and improving fuel efficiency.
• Cools down engine components. Engine oil reduces friction within the engine. When engine oil loses its lubricating characteristics, friction between important engine components increases, causing critical components to wear more quickly.
• Helps to notice unrelated issues. A visit to the workshop is a great way to inspect a vehicle’s health. A quick vehicle inspection can reveal hidden problems that could later contribute to a hefty repair bill.

Types of motor oil for your vehicle

Each type of motor oil has a unique set of characteristics that can improve the performance of your car. Understanding the role of motor oil might help you decide which type is best for your vehicle.

• Traditional (mineral) motor oils. Due to their thickness in various conditions, traditional (mineral) oils are commonly used in classic cars or vehicles with a higher mileage.
• Semi-synthetic motor oils. Semi-synthetic oils are a mixture of fully synthetic and traditional (mineral) oils designed to keep costs low while improving the lubrication properties of mineral oil.
• Synthetic motor oil. Most modern vehicles require synthetic oil because of its ability to protect the engine from wear, oxidation, and corrosion.

What is oil viscosity?

Oil viscosity refers to how well a lubricant flows at a given temperature. Thin oils have lower viscosity and flow more easily at low temperatures than thicker oils with higher viscosity. Furthermore, thin oils reduce engine friction and help engines start more easily in cold weather. Meanwhile, thick oils are better at maintaining oil pressure in high temperatures and loads.

The incorrect oil viscosity selection for your car's engine could lead to a specific selection of problems. For example, filling up your car’s engine with thicker oil than the manufacturer intended to use will lead to a “Check Engine” dashboard warning light, excessive engine wear, and worse fuel efficiency.

Oil specifications

SAE (Society of Automotive Engineers) distinguishes 14 viscosity grades – 6 winter grades with a number before the letter W (0W, 5W, 10W, 15W, 20W, 25W) and 8 summer grades with a number after the letter W (W8, W12, W16, W20, W30, W40, W50, W60).

Winter grade oils are thinner, thus having a better flow rate at lower temperatures. Summer grade oils indicate the oil's viscosity at high temperatures. The higher the number, the bigger the viscosity, resulting in better engine protection in higher temperatures.

Engine oil quality classifications

There are 2 engine oil quality classifications: API (American Petroleum Institute) and ACEA (Association des constructeurs Européens d'Automobiles).

The classification adopted in the United States (API) is divided into 2 groups: "S" for petrol-driven engines and "C" for diesel engines.

In Europe, applications for motor oils are divided into 4 groups: "A" for petrol-powered engines, "B" for diesel engines, "C" for diesel engines with particulate filter compatibility, and "E" for commercial diesel vehicles.

Oil change cost

The average engine oil change takes just 30 to 45 minutes, making a scheduled oil change one of the least demanding car maintenance tasks.

While engine oil could be changed quite swiftly, the oil change cost depends on a rather long list of factors.

Oil change cost factors

The most significant oil change cost factor is whether you plan to carry out the work yourself or have it done in a workshop. However, the these are the biggest cost factors of the oil change:

• Engine size
• Engine type
• Engine oil viscosity
• Engine oil manufacturer

Furthermore, if you plan to change the engine oil yourself, always check how much your vehicle's engine requires. If you overfill it, the excess oil will eventually enter the exhaust system and burn, producing white smoke.

Also, modern cars come with an oil change indicator system. This system displays the remaining days and miles until you should schedule a visit to a workshop. You'll need a suitable OBD2 scanner with the necessary software to reset this indicator.

Request the service history, as vehicle mileage can be faked

Maintaining proper oil change practices is the cornerstone of ensuring your vehicle's long-term engine performance and durability. That's why having a clean and meticulously documented vehicle history is an absolute necessity if you want a hassle-free car in your driveway.

In today's used car market, it's common to encounter numerous vehicles with concealed defects, altered mileage readings, and even falsified service history records. They would mistakenly suggest a recent scheduled engine oil change, while, in truth, it was done a few years ago. However, you can overcome all of these risks.

Since every car has a unique vehicle identification number, by using a VIN decoder tool you can gain access to a vehicle history report, which contains data from over 900 data sources, including states registries, insurance companies, law enforcement databases, and more.

If you have any suspicions about odometer rollback, equipment that doesn’t meet the manufacturer’s specifications, or if you spot incorrect color shades on body parts, a vehicle history report can help you either confirm or refute the doubts.