Many car owners wonder if they can service their own car instead of paying for a professional mechanic. While DIY car servicing can save money and be a fun and rewarding experience, it requires knowledge, the right tools, and an understanding of legal and warranty implications. In this guide, we’ll cover everything you need to know, from the basics of servicing your own car to the risks, benefits, and legal considerations.

Is It Legal to Service Your Own Car?

Servicing your own car is completely legal in the UK. However, there are some important considerations, such as:

• Ensuring you follow manufacturer guidelines.
• Keeping records of any service work done.
• Using approved parts if your car is under warranty.
• Properly disposing of fluids like engine oil.
• Some policies require a certified mechanic to carry out services.

What is a car service?

Is It Easy to Service My Own Car?

Before getting started, it’s important to note that DIY servicing shouldn’t replace professional maintenance entirely. 

The difficulty of servicing your car depends on your technical knowledge, tools, and the type of service needed. Basic tasks like oil changes or air filter replacements are relatively simple, while more complex jobs, such as brake fluid replacement or timing belt changes, require advanced skills and specialised tools.

Pros and Cons of Servicing Your Own Car

Pros

• Cost Savings – DIY servicing is often cheaper than a garage.
• Learning Experience – Helps you understand how your car works.
• Convenience – No need to book an appointment.

Cons

• Lack of Professional Expertise – Mistakes can lead to costly repairs.
• Time-Consuming – DIY servicing takes longer than a professional service.
• Limited Tools & Equipment – Some jobs require specialized tools.

	DIY Servicing	Professional Garage
Cost	Low (£50-£100)	High (£150-£300)
Convenience	Must have time, skills & tools	Quick, no effort required
Warranty Safe?	No, unless performed exactly to manufacturer’s standards with approved parts (and documented)	Yes, if done by a VAT-registered garage using approved parts
Skill Required	Intermediate	None
Risk of Mistakes	High	Low

Common DIY Car Servicing Mistakes & How to Avoid Them

1. Using the Wrong Oil

The Mistake:

• Different cars require specific oil grades and viscosity (e.g., 5W-30, 10W-40).
• Using the wrong oil can cause increased engine wear, reduced fuel efficiency, and even long-term engine damage.
• Some modern engines require fully synthetic oil, while others may be designed for semi-synthetic or mineral oil.

What to do: 

• Check your car’s manual for the manufacturer-recommended oil type and specifications.
• Use high-quality oil that meets the required industry standards (e.g., ACEA, API, or manufacturer approvals like VW 507.00).
• If unsure, it’s always better to have a professional mechanic do it. 

2. Over-Tightening Screws & Bolts

The Mistake:

• Many DIYers over-tighten bolts, screws, and drain plugs to prevent leaks or loosening.
• This can lead to stripped threads, broken bolts, and damaged components, especially in soft metals like aluminium.
• Over-tightening spark plugs can damage the cylinder head and make removal difficult in the future.

What to do:

• Always use a torque wrench and apply the manufacturer-specified torque settings.
• Refer to the vehicle’s service manual for recommended torque values, especially for critical components like wheel nuts, spark plugs, and sump plugs.
• When installing an oil filter or spark plug, hand-tighten it first and then follow the recommended additional turns as specified in the manual.
• Apply anti-seize grease to spark plug threads where required to prevent seizing without over-tightening.

3. Skipping Brake Fluid Checks

The Mistake:

• Brake fluid absorbs moisture over time, which reduces braking performance and can lead to internal corrosion.
• Low or contaminated brake fluid can cause a soft brake pedal, longer stopping distances, or brake failure.
• Some DIYers only check the brake fluid level but do not change it regularly, even though it degrades over time.

What to do:

• Check the brake fluid reservoir regularly to ensure the level is within the recommended range.
• Brake fluid should be clear or light amber; if it appears dark, it needs replacing.
• If the fluid level is low, inspect for potential leaks or worn brake pads rather than just topping it up.
• Use the correct brake fluid type (e.g., DOT 4, DOT 5.1) as specified in your owner’s manual.
• Replace brake fluid every two to three years or as recommended by the manufacturer to maintain safe braking performance. Anything to do with brakes – we would recommend sticking to professional mechanics as it’s a matter of safety!

4. Incorrect Coolant Mixing

The Mistake:

• Using the wrong coolant type or an incorrect water-to-coolant ratio can lead to overheating or corrosion.
• Mixing different coolant types (e.g., OAT and IAT) can cause chemical reactions that form sludge inside the cooling system.
• Some people use only water instead of coolant, which reduces the boiling point and leads to rust buildup.

What to do:

• Always check the car’s manual for the recommended coolant type (e.g., ethylene glycol-based, OAT).
• If topping up, use the same type of coolant already in the system—never mix different coolant types.
• Follow the manufacturer’s recommended coolant-to-water ratio (often 50:50).
• Flush and replace coolant at the intervals specified in the manual to prevent buildup and blockages.

5. Neglecting Tyre Pressure & Tread Depth

The Mistake:

• Driving with incorrect tyre pressures can lead to uneven wear, poor fuel efficiency, and reduced grip.
• Not checking tread depth can result in illegal tyres that compromise safety, especially in wet conditions.

What to do:

• Check tyre pressures at least once a month and before long journeys, using a reliable tyre pressure gauge.
• Inflate tyres to the manufacturer’s recommended pressure (usually found in the manual or inside the driver’s door frame).
• Check tread depth regularly—UK law requires a minimum of 1.6mm across the central three-quarters of the tyre.
• Use a 20p coin to check tread depth: if the outer rim is visible when inserted into the tread, the tyre needs replacing.

PLEASE NOTE: DIY servicing should be limited to basic car checks and routine maintenance, such as oil changes, air filter replacements, and tyre pressure checks. We recommend that complex repairs and safety-critical work, like brake servicin, and electrical diagnostics, should always be left to trained professionals and qualified mechanics.

How Do I Dispose of Old Engine Oil?

Used engine oil is hazardous waste and must be disposed of responsibly, you can take it to a local recycling centre. 

Most Household Waste Recycling Centres (HWRCs) accept used engine oil. These centres are managed by local councils and provide designated oil disposal facilities.

• Visit your local council’s website to check their waste disposal facilities.
• Use Recycle Now’s oil recycling locator to find nearby centres that accept motor oil.
• Ensure you store the oil in a sealed, leak-proof container (such as the original oil bottle or a purpose-made oil drain container) before transporting it.

Will My Warranty Be Valid If I Service My Own Car?

DIY servicing does not maintain warranty validity unless you can prove the work was done correctly and with manufacturer-approved parts and fluids.

Under the Block Exemption Regulation, you are not required to use a main dealer for servicing, but the work must be carried out by a VAT-registered garage using approved parts.

Keeping detailed service records (receipts for parts, log of work done, and mileage at service intervals) may help in case of warranty claims, but it does not guarantee validity if the manufacturer disputes it.

Many extended warranties and finance agreements (PCP/lease deals) require servicing at an approved garage to maintain the warranty and vehicle value.

A guide to car servicing and warranties.

Can I Get a Service Stamp If I Do My Own Service?

Most garages will not stamp a service book unless they have carried out the work themselves. A stamped service book is often required to maintain warranty coverage, resale value, and PCP/lease agreements.

However, if you choose to service your car yourself, you can still maintain a reliable service history by:

Recording the date, mileage, and details of the service (e.g., oil change, filter replacement).

Keeping receipts for engine oil, filters, spark plugs, brake pads, and other consumables to prove that you’ve used approved parts.

Does a Service Stamp Matter?

For older cars out of warranty, detailed records and receipts may be enough to prove regular maintenance. However, for newer cars, missing service stamps can:

• Reduce resale or trade-in value
• Affect warranty coverage
• Violate PCP/lease agreements

If maintaining a full service history is important, it’s often best to have the car serviced by a garage that can update records digitally and stamp your book.

Should I Service My Own Car or Use a Mechanic or Garage?

If you have the skills and tools, a DIY service for very basic checks can save money. However, for warranty validity, safety, and complex repairs, using a qualified mechanic or garage is often the best choice.

While servicing your own car can be rewarding and cost-effective, it comes with risks and challenges. If you’re confident in your skills and have the right tools, a DIY service may work for you. However, if you’re unsure, a professional mechanic can ensure a reliable, warranty-compliant service.