That “small” car problem you’re ignoring could already be costing you hundreds, and left untreated, it could cost you thousands. From skipped services to ignored warning lights, poor maintenance decisions are turning minor issues into major repair bills for drivers. In fact, around 28%of drivers haven’t done any repairs or maintenance in 12 months. Meanwhile, 19% of drivers trust their own judgement over their car’s warning lights.
While attempting to do your own car maintenance may sound practical, modern engines are much less forgiving than older models. This is because they rely on precise electronic systems, advanced sensors, and tightly engineered components that can be easily damaged or thrown out of calibration without the correct tools and expertise.
As a result, even small maintenance mistakes (particularly involving engine oil) can escalate into expensive car repairs for unsuspecting drivers.
With this in mind, we’ll be exploring the 4 most common maintenance mistakes car owners make and the impact and damage they can cause to your car.
Mistake 1: Skipping or delaying oil changes
Even when the correct oil is used, neglecting regular oil changes can still lead to serious engine damage. As it degrades, it breaks down and forms sludge, which can clog passages and prevent proper oil circulation. By missing oil changes, you risk your engine overheating, poor fuel efficiency, an increase in harmful emissions and severe engine failure.
Despite these risks, over 28% of car owners don’t carry out any recommended maintenance themselves, suggesting they also delay servicing. Routine maintenance intervals are recommended by your vehicle manufacturer to keep your vehicle safe, reliable and to extend its lifespan. By ignoring these recommendations, you increase the likelihood of mechanical failure, potentially exposing yourself to costly repairs.
Common car repairs as a result of delaying oil changes
Delaying oil changes can have a significant impact on your vehicle. What might start as a small corrective repair can soon progress to damage beyond repair, so it’s important to address minor issues early to prevent the following:
- Oil pump failure: Missing oil changes can lead to sludge buildup as it becomes contaminated and degrades. This restricts the flow of the oil and makes the pump work harder, leading to premature wear and pump failure.
- Bearing damage: Oil loses its ability to maintain a consistent viscosity (thickness) when it breaks down, so it can no longer form a protective film that prevents components from touching. Bearings are sensitive to oil contamination and can grind against metal surfaces, leading to friction and wear.
- Engine rebuild or replacement: When oil turns to sludge, it loses its lubricating properties. This can cause extreme friction between critical components and severe damage that may require a complete engine replacement.
Neglecting oil change intervals can not only result in expensive engine damage, but it might also be uneconomical to fix. These could cost an average of:
| Replacement Part | Estimated Cost GBP £ | Estimated Cost USD $ | Estimated Cost AED د. إ. | Estimated Cost INR ₹ |
|---|---|---|---|---|
| Oil pump replacement | £600-£800 | $801.49-$1,068.66 | 2,944.58-3,926.10 | ₹ 74,244.18- ₹ 98,992.24 |
| Camshaft and bearing repairs | £360-£400 | $480.90-$534.33 | 1,766.75-1,963.05 | ₹ 44,546.51- ₹ 49,496.12 |
| Engine Replacement | £1,500-£8,000 | $2,003.73-$10,686.56 | 7,361.44-3,9261.02 | ₹ 185,610.45- ₹ 989,922.40 |
Mistake 2: Ignoring dashboard warning lights
Dashboard warning lights are a key safety feature of your car, as they can alert you to immediate hazards and potential failures. By responding to warnings early, you can prevent repairs and breakdowns. However, if you choose to ignore the warnings, it can lead to irreversible damage.
Electrical warnings and associated repairs
Battery and sensor warnings are often deprioritised, with almost 50% of car owners delaying investigation by a mechanic by a few days or failing to seek professional help entirely. Once again, this can lead to major failures and expensive repairs, including:
- Battery replacement: Many modern vehicles have stop/start batteries, which put higher demands on the battery as the car is always restarting. Over time, they are not able to hold power and may need replacing once the dashboard warning light comes on.
- Sensor replacement: Car sensors, especially oxygen sensors, are exposed to extreme heat and harsh chemicals in the exhaust system. They need to be changed regularly because they can degrade over time and lead to poor engine performance.
Once parts and labour have been factored in, it can often cost several hundred pounds to repair electrical faults, especially if you have been ignoring them.
Overheating warnings and potential repairs
The cooling and oil systems in your car are closely linked to manage the engine’s temperature and prevent overheating. By ignoring the temperature warning lights, you risk premature engine wear.
- Radiator cooling fan replacement: By the time the temperature warning light comes on, the engine may already be operating outside its optimal temperature range, or it may have low coolant. This often means the fan is struggling or it’s already stopped working, and if you continue to drive, the fan can fail.
- Engine oil cooler replacement: If your engine is already overheating, the engine oil cooler can fail. This is usually caused by extreme temperatures that lead to warped metal, cracked plastic or failed seals, which can allow the oil and coolant to mix.
These repairs can be avoided by acknowledging warning lights as soon as they come up and seeking professional help. If you don’t, you could face the following repair costs:
| Replacement Part | Estimated Cost GBP £ | Estimated Cost USD $ | Estimated Cost AED د. إ. | Estimated Cost INR ₹ |
|---|---|---|---|---|
| Battery Replacement | £300-£350 | $400.75-$467.54 | 1,472.29-1,717.67 | ₹37,122.09-₹43,309.11 |
| Radiator cooling fan replacement | £1,100-£1,300 | $1,469.40-$1,736.57 | 5,398.39-6,379.92 | ₹136,114.33-₹160,862.39 |
| Engine oil cooler replacement | £140-£180 | $187.01-$240.45 | 687.07-883.37 | ₹173,23.64-₹222,73.25 |
Mistake 3: Using the wrong engine oil
Modern engines require precise oil grades that are specified in your owner’s manual. The right engine oil for your car may be influenced by your driving style or the climate you drive in, but it will always be specified by your manufacturer. Using the wrong oil compromises engine lubrication, cooling and proper component protection.
Even oils with the same viscosity grade can differ significantly in formulation. Additive packages vary between products and are designed to control wear, manage deposits, maintain viscosity stability and protect modern emission systems such as catalytic converters and diesel particulate filters.
That doesn’t stop 17% of drivers from attempting to change their own engine oil. Using the wrong engine oil can lead to engine overheating, unusual engine noises, poor performance, premature engine wear, and, in severe cases, increase the likelihood of major engine damage.
Common car repairs as a result of using the wrong engine oil
Typical failures as a result of using the wrong oil include:
- Turbocharger failure: Turbochargers operate at extremely high speeds and high temperatures, so they rely on a very precise thin film of oil. If the wrong oil is used, the film is broken, which can lead to oil starvation, contamination, thermal breakdown and immediate failure.
- Timing chain damage: If your oil is too thick, too thin or the wrong specification, the timing chain can stretch, or develop excessive wear, leading to noise, poor engine timing and, in severe cases, engine damage.
- Oil pump failure: Oil that is too thick can cause excessive strain and wear, leading to high pressure and poor flow during cold starts. Meanwhile, If oil is too thin, it may struggle to maintain a protective film under load, increasing wear and reducing oil pressure.
A combination of these failures can result in repairs costing thousands. For modern cars, you could see the following costs for replacement parts.
| Replacement Part | Estimated Cost GBP £ | Estimated Cost USD $ | Estimated Cost AED د. إ. | Estimated Cost INR ₹ |
|---|---|---|---|---|
| Turbocharger replacement | £1,300-£1,500 | $1,736.57-$2,003.73 | 6,379.92-7,361.44 | ₹160,862.39-₹185,610.45 |
| Timing chain replacement | £450-£500 | $601.12-$667.91 | 2,208.43-2,453.81 | ₹55,683.14-₹61,870.15 |
| Oil pump replacement | £600-£800 | $801.49-$1,068.66 | 2,944.58-3,926.10 | ₹74,244.18-₹98,992.24 |
Mistake 4: DIY maintenance without understanding modern engines
DIY maintenance can be useful for simple tasks, but modern engines leave little room for error. However, without an understanding of modern engines, you should seek the help of a qualified mechanic. That is because modern engines have tighter tolerances and less room for errors, so even the smallest mistake can lead to expensive repairs.
Despite the risk of failure, this doesn’t stop car owners from attempting to take on DIY tasks themselves, with under-35s significantly more likely to take on the challenge of completing their own oil change than older drivers. But what are you risking by taking on DIY car maintenance yourself?
Common car repairs as a result of DIY maintenance
Attempting to fix your car yourself might seem like the more cost-effective option, but it can actually end up being more expensive than the initial job. Some repairs you may face include:
- Oil leaks leading to oil starvation: Common mistakes when completing oil changes yourself include using the wrong components and failing to tighten parts properly. These can lead to oil leaks and starvation, which can cause friction, overheating and irreversible damage.
- Turbo failure: Turbochargers spin faster than 200,000 RPM, so correct lubrication is essential. However, poor DIY jobs can cause oil starvation, leaks, and damage from foreign objects. This can cause immediate power loss, making your car undrivable.
- Sensor faults caused by contamination: Poorly installed sensors are prone to dirt, oil, moisture or chemical contamination, leading to false readings if the sensor is damaged. This can cause inaccurate data and poor engine performance.
Given the damage that DIY repairs can lead to, it’s often better to leave technical car repairs to a qualified mechanic. Otherwise, you may face the following repair costs:
| Replacement Part | Estimated Cost GBP £ | Estimated Cost USD $ | Estimated Cost AED د. إ. | Estimated Cost INR ₹ |
|---|---|---|---|---|
| Turbocharger Replacement | £1,300-£1,500 |
$1,736.57-$2,003.73 |
6,379.92-7,361.44 | ₹160,862.39-₹185,610.45 |
Conclusion
Many of the most expensive repairs stem from issues that began as minor and manageable faults. Early intervention is more important than your ability to carry out the work yourself, and if you are not confident and qualified, it’s best not to attempt car repairs at all. For modern engines, especially, regular maintenance and using the correct oil, as recommended by your manufacturer, is key to car longevity and safety on the road.
Sources & methodology
Behavioural insights referenced in this article are drawn from third-party data on car maintenance. Repair outcomes and costs are indicative and based on common repair scenarios. Actual costs vary depending on vehicle model, age, condition and severity of damage.
Repair costs
All repair costs are estimates based on averages in February/March 2026.