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? 

You will face many issues if you don’t change your engine oil. These include increased wear, worse MPG, overheating, increased emissions, clogged systems, voided warranty, decreased resale value, and potential engine failures.  

So, there’s nothing positive to be gained from putting your oil change off. 

The oil in your engine reduces friction and heat by lubricating the moving parts. When the oil is fresh, it lubricates at peak efficiency and minimises wear on the engine components. 

When the oil breaks down, the two faces will wear significantly faster. This will be hard to notice on the camshafts, but over time, this increased wear on the cylinder bores will create a significant loss in power. 

Here are the eight problems you’ll encounter if you don’t change your oil frequently.  

1. Overheating 

Not only does oil lubricate, but it also plays a crucial role in cooling down certain parts of the engine. Race cars often have dedicated oil coolers, but many run-of-the-mill cars also implement designs to reduce oil temperature.  

Surpassing oil change intervals can lead to a reduction in oil-based cooling and excessive heat from increased friction.  

Both symptoms are not good for an engine, and more heat generally equates to less efficiency, more wear and a higher chance of something breaking permanently. 

2. Reduced fuel efficiency 

Not changing your oil on time could increase your fuel consumption. As a consequence of the increase in heat, reduction in compression due to worn cylinders and a lack of cooling, fuel efficiency will likely decrease.  

Over time, this could significantly increase fuel costs, probably more so than the cost of an oil change! 

3. Increased emissions  

A decrease in fuel efficiency generally coincides with an increase in harmful emissions, mainly by burning oil due to excessive engine wear.  

A small amount of engine oil will always make its way into the engine's combustion chamber, but the more wear to the cylinder walls, the more will enter and burn off as nasty emissions.  

4. Systems will clog with dirt and debris 

Many complex mechanisms rely on good oil flow to function properly. Examples include variable valve timing, turbochargers and engine breathers. 

VVT or Vanos systems often use the engine's oil pressure to operate. These are extremely precise systems, and any oil pressure, quality, or viscosity decrease can affect them. In the best case, the engine stops varying the valve timing properly.  

In the worst case, the Vanos system clogs and requires removal, replacement, or cleaning. 

5. Turbos can fail and destroy your engine 

Extremely common in modern cars, turbochargers utilise waste energy from the exhaust to increase 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.  

Turbos spin incredibly fast, more than 10,000 RPM. To turn efficiently, they need a substantial supply of oil; a partial or momentary pause in the oil supply can cause the turbine to overheat and fail. 

Because half of the turbo is in the path of air entering the engine, if shards of the turbine break off due to catastrophic failure, they can quickly enter the engine, causing severe damage.  

6. Worse performance 

If you’ve ever waited a long time between oil changes, you probably noticed a difference in how well the car performed after the oil change was complete. Simply put, with fresh new oil, your engine’s spinning parts can move smoothly and use less power to make their revolutions.  

7. Voiding your warranty  

The manufacturer’s warranty for a new car can last as long as a decade — if you stick to its prescribed maintenance schedule. Skip too many oil changes, and the warranty terms might render it void.  

If there’s ever a major repair, it could cost you thousands more than it would have if the warranty was still valid.  

8. Reduced resale value  

Resale value probably isn't the first thing on your mind when you buy a car. Eventually, however, the day comes when you want to sell or trade-in your vehicle for a new one.  

Keeping to a schedule of regular oil changes will increase your car's resale value. The engine will perform noticeably better on inspection or in a test drive. Keep a detailed record of oil changes and other regular maintenance; you might even improve your sale price.  

What are the benefits of changing your oil on schedule? 

Keeping your engine healthy with fresh oil has many benefits, including preventing engine failure, reducing engine wear, increasing resale value, and improving your car maintenance.  

Catching other problems early  

When you have an oil change done, it allows the mechanic to visually inspect your car under the bonnet. They'll see the battery, air filters, brakes, and whatever else they have on their standard list. That means they'll be able to note any potential problems before they happen.   

It helps you keep to a schedule  

Every car has a suggested manufacturer’s maintenance schedule for regular servicing. Focusing on oil changes makes it easier to track the intervals and ensure you’re being seen by a mechanic at least once a year.  

Your mechanic will probably remind you about any upcoming scheduled maintenance in addition to the oil change so you can book an appointment on the spot.  

Stopping catastrophes from happening  

If your engine oil turns to sludge, it won't be able to lubricate anymore, and your car engine will seize up. That means the metal parts fuse under intense friction and heat. It's almost impossible to fix, probably requiring a new engine or even a write-off of the car. 

Does missing oil changes cause engine wear? 

Yes, oil prevents wear by minimising the friction between the engine's moving parts. Oil also has a limited service life, meaning it breaks down and stops providing the same level of lubrication, leading to rapid wear.  

Who can change my oil? 

Almost anyone can do an oil change. The tools needed to change your car’s oil are not complex or expensive, but it does need to be done safely, as it usually requires jacking up the vehicle and crawling under the engine. 

If you don’t want to change it yourself, you should be able to easily find a garage for an oil change near you. Almost any garage can offer oil changes as it is one of the most basic tasks a mechanic can do.  

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

Is my oil changed during a service? 

As one of the most essential car service elements, oil changes are always included in interim and full services. This generally also consists of an oil filter change to keep the new oil cleaner for longer. 

It’s good practice to check what oil grade and quality the garage will be using, especially if you’re not taking your car to a primary dealer for servicing. We have a handy guide on oil grades here. 

Is my oil changed during an MOT test? 

Whilst things like engine oil leaks would be noticed, the MOT test does not include an oil level or quality check, or an oil change. For this reason, booking a service at the same time as an MOT test is a good idea.  

An annual MOT test is a legal requirement for cars over three years old. The test includes checking all safety critical systems such as brakes, suspension, and tyres.  

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

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 

Historically, oil changes were determined by how many miles you’d driven since the last change. Today, we can use three key factors to estimate when you need to change your oil. These include: 

• Vehicle type 
• How you drive 
• The age of the vehicle 

You must look at vehicle type, as some require different oil change times than others. Similarly, the length of your average drive will affect your oil changes. Short trips and inner-city drives are more demanding on your engine and require more oil changes. 

Finally, older cars generally require more maintenance and oil changes than newer cars. So, if you’ve just bought a new car, you won’t have to change your oil as often as older ones. 

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

Put simply, no. The oil should be changed for most cars every 3-6,000 miles. For most cars, not changing your oil for over a year means missing two separate changes, which could seriously damage your engine. 

Making time for something as mundane as an oil change is an annoyance, but it's vital to your car's health. If you want your car to last a long time and perform well, take the time to get the oil changed. Expect to spend more if you don't. 

What are the signs that suggest an oil change? 

Over time, the engine will exhibit signs that you need an oil change, like increased fuel consumption, reduced performance, and smoky exhaust fumes. 

Other 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 

The danger appears because unlike knocking suspension or a blowing exhaust, not changing the oil does not make a loud or easily noticeable difference, at least for the first few months.  

However, once these symptoms start to show, it may well mean your engine is seriously damaged already - so follow those service intervals! 

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

You might find a sticker inside your engine bay that states a mileage. These are often used to record when an oil change was last done. It's best to limit the miles past the sticker as much as possible, even having the oil change done in advance. 

The trouble with oil change stickers is that they might not be 100% accurate, as there is no way to officiate the work. 

We generally recommend using your car's service book. That way, there can be no confusion over what was done and by whom. The book can also be passed to a prospective buyer, giving a detailed car history. 

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

Some manufacturers now recommend an oil change every 12-15,000 miles, so it may well be that 10,000 is fine. But as the previous point, it's best to check your owner's manual alongside the service records for peace of mind.  

What happens if you don’t change your oil - The bottom line 

Staying on top of your oil changes is a guaranteed way to keep your car healthy and prevent avoidable problems. This will make driving safer and save you lots of money in the future. Don’t put it off! 

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