It's easy to forget car maintenance, especially regarding oil changes. We jump in and drive every day, expecting everything to run well. But you need to keep on top of maintenance for a healthy car. 

Today, we're explaining what happens if you don't change your oil and how long you can go without an oil change. Let's get into it! 

What happens if you don’t change your oil? 

Not changing your engine oil can lead to issues like increased wear, worse MPG, overheating, higher emissions, clogged systems, a voided warranty, decreased resale value, and potential engine failures.

There’s nothing positive to be gained from putting your oil change off. 

So, what happens when you don't change your oil? Here are the eight problems you’ll encounter if you don’t change your oil frequently.  

1. Overheating 

Oil lubricates and cools engine parts. While race cars have dedicated oil coolers, many regular cars also reduce oil temperature. Exceeding oil change intervals reduces oil-based cooling and increases friction heat.

Both symptoms harm the engine, as more heat leads to less efficiency, more wear, and a higher risk of permanent damage.

2. Reduced fuel efficiency 

Skipping oil changes can increase fuel consumption due to higher heat, reduced compression, and poor cooling, leading to higher fuel costs over time—likely more than the cost of the oil change itself.

3. Increased emissions  

Decreased fuel efficiency often leads to higher harmful emissions, primarily from burning oil due to engine wear. More wear on cylinder walls means more oil burns off as pollutants. 

4. Systems will clog with dirt and debris 

Complex mechanisms like variable valve timing, turbochargers, and engine breathers depend on good oil flow. 

Systems like VVT or Vanos use oil pressure for precision, and any drop in oil quality or viscosity can disrupt their function. This can lead to potential clogging and costly repairs.

5. Turbos can fail and destroy your engine  

Turbochargers, common in modern cars, use exhaust waste energy to boost power and efficiency. Turbos are responsible for the modern spate of small, high MPG-achieving engines such as those found in Ford, Audi and Volkswagen vehicles. 

They spin over 10,000 RPM and require a steady oil supply; interruptions can cause overheating and failure. If a turbo fails, debris can enter the engine, leading to severe damage.

6. Worse performance 

If you've waited long between oil changes, you likely noticed improved performance afterwards. Fresh oil helps your engine's parts move smoothly and use less power.

7. Voiding your warranty

A new car’s warranty can last up to a decade if you follow the maintenance schedule. Skipping oil changes may void the warranty, potentially leading to costly repairs later.

8. Reduced resale value  

While resale value might not be a priority when buying a car, regular oil changes will boost it when you sell or trade-in. A well-maintained engine performs better during inspections and test drives, and detailed records can enhance your sale price.

How long can you go without an oil change?

Experts suggest you should change your car’s oil every 3,000 miles.

But this doesn’t apply to all modern cars. Instead, you should check your owner’s manual. This will give you specific information, and you won’t have to rely on vague estimates. 

Factors that affect oil change times 

Oil change intervals were once based solely on mileage. Today, consider three factors: 

• Vehicle type
• Driving habits
• Vehicle age

Different vehicles and driving conditions require varying oil change frequencies, with older cars needing more frequent changes compared to newer ones.

Is it okay to go a year without an oil change? 

No, you should change your oil every 3,000 to 6,000 miles. 

Skipping oil changes for over a year can lead to serious engine damage. While it might be a hassle, regular oil changes are crucial for your car’s longevity and performance, and neglecting them could cost more in the long run.

What are the benefits of changing your oil on schedule? 

Fresh oil keeps your engine healthy by preventing failure, reducing wear, boosting resale value, and improving maintenance. Here are some extra benefits:

• Catching Other Problems Early: An oil change allows the mechanic to inspect your car’s battery, air filters, brakes, and more, identifying potential issues before they escalate.
• Helps You Keep to a Schedule: Regular oil changes help you track and adhere to your car’s manufacturer maintenance schedule, ensuring annual mechanic visits.
• Prevents Catastrophes: Fresh oil prevents sludge buildup, which can cause severe engine damage. Without proper lubrication, your engine could seize, potentially requiring a costly replacement or write-off.

Does missing oil changes cause engine wear?

Yes, oil reduces wear by minimising friction between engine parts. However, it breaks down over time and loses its lubricating effectiveness, leading to increased engine wear.

Who can change my oil?

Oil changes are simple and require basic tools, but they need to be done safely, often involving jacking up the car. If you prefer not to do it yourself, most garages offer oil changes as a basic service.

Is my oil changed during a service? 

Oil changes are a key part of interim and full services, usually including an oil filter change.

Check the oil grade and quality used, especially if not going to a primary dealer. We have a handy guide on oil grades here.

Split the cost of repairs into interest-free monthly repayments and choose from thousands of service partners nationwide.

Is my oil changed during an MOT test?

The MOT test does not check oil level, or quality, or perform oil changes. It’s wise to book a service with your MOT. An annual MOT, required for cars over three years old, covers safety systems like brakes, suspension, and tyres.

Check out our guide here for more on precisely what an MOT covers. 

Signs you need an oil change

Signs you need an oil change include increased fuel consumption, reduced performance, and smoky exhaust fumes.

Additional signs you need an oil change include: 

• Unusual engine sounds
• Dirty or grimy oil
• Low oil levels
• Dashboard warning lights
• Abnormal vibrations
• Burning smell
• Clunky gear shifts

Unlike suspension issues or exhaust problems, oil change neglect isn't immediately noticeable.

By the time symptoms appear, your engine may already be seriously damaged, so stick to service intervals.

How many miles can you go over an oil change sticker?

You might find a sticker in your engine bay indicating the last oil change mileage. It’s best not to exceed this mileage and consider changing the oil earlier. However, stickers can be inaccurate, so using your car’s service book is recommended for precise records and resale value.

What happens if you don't change your oil for 10,000 miles? 

Some manufacturers recommend oil changes every 12-15,000 miles, so 10,000 might be fine. 

Like the previous point, you should always check your owner's manual and service records for confirmation.

Final thoughts on what happens if you don’t change your oil 

Regular oil changes are essential for maintaining your car’s health and preventing costly problems. Keeping up with them ensures safer driving and saves you money in the long run. Don’t delay—stay on top of your oil changes!

Need an expert opinion? Book your vehicle with a reliable repairer and split the cost into interest-free monthly payments with Bumper. 

Author - Joseph Law

Joseph has been writing about cars for over seven years and writing for Bumper for over two, blending his passion for automobiles with a talent for storytelling.

Joseph has written about engineering and cars for Autozilla, Komaspec, and several engineering manufacturers. When he's not writing or tinkering with one of his five cars, Joseph dreams of owning an Alfa Romeo 33 Stradale.