Can you service your car yourself?
Cars have become complex machines but routine servicing is still a simple process. With dealer labour rates and parts costs higher than ever, the temptation to DIY is understandable.
- Manufacturer and extended warranties need documented servicing
- On cars over ten years old there’s little benefit to dealer visits
- Routine servicing involves more than just engine oil and filters
Doing your own maintenance was once a cornerstone of running a car on a reasonable budget, even for relatively new models. Since the introduction of electronic ignition and fuel injection it has become unusual for non-enthusiast owners to work on their own cars. It’s not just the engineering that improved — fuel and lubricants are made to higher standards, while recommended service intervals can be up to two years apart.
Most manufacturers offer service plans to keep more recent models in the network for a very reasonable price. The illusion of sealed-for-life, maintenance free disposable cars looks almost tangible.
Look at the reliability statistics for many popular cars and you soon realise 'sealed-for-life' is based on the manufacturer’s hope that the cars last long enough for the second owner’s finance to be paid off — around eight to 10 years.
Yet over 30% of the cars on Britain’s roads are more than twenty years old — and that number could be higher if people were prepared to take better care of their vehicles and pay for consumables like clutches and suspension.
When do cars need servicing?
Fleets and car owners alike want long service intervals and low costs, so the gap between professional attention can be up to two years or 20,000 miles. Those roadside mechanics of Britain’s motoring past would be rolling their eyes at the very thought. Older cars were more prone to leaks and burning oil, so frequent attention was unavoidable.
With modern cars it is still best to change oil and filters frequently. Your car will last longer, be more fuel efficient and you’ll spot early warning signs for other issues
Money matters, so a car being beyond uneconomic repair, even if it is due to the cost of consumable items, is not unreasonable. Once a car has covered over 150,000 miles or 12 years of average use, it is likely to need a lot of parts replacing even if the body, interior and electrics have held up well. It’s a credit to manufacturers that even the cheapest, most basic models sold in the past 30 years seem able to achieve that milestone with ease.
So when a vehicle fails at less than 100,000 miles, or seven years old — the typical boundaries of approved-used schemes — then something isn’t right. We’re seeing common issues crop up across brands, such as failing timing chains, sometimes on cars less than five years or 50,000 miles old.
Why? Sometimes it’s bad design. Sometimes, it’s by design.
Servicing most modern cars is relatively easy with just a few affordable tools. It’s also cleaner and less messy than before, though our first bit of advice is wear disposable gloves when working on any part of the car. It’s entirely possible for most people to manage their own car servicing and some repairs.
Does servicing a car yourself invalidate the warranty?
Technically, it shouldn’t, but you don’t want the argument. If your car is covered by the original manufacturer warranty, or is within the scope of service-activated extended warranties such as Toyota’s 10-year, 100,000 mile coverage, it’s still best to pay for the annual service and have it seen by an approved garage or main dealer.
That doesn’t mean you can’t maintain the car yourself in addition to the scheduled maintenance. You can also get repairs done without visiting a dealer. We advise that you keep records of what you buy, when you replaced parts and avoid any tinkering with any safety-related components.
There are reasons other than the warranty to keep a modern car looked after by main dealers until it’s coming up for 100,000 miles or eight years old, however, such as extended warranty or goodwill cover for failing parts.
What is goodwill cover?
Some cars fail prematurely with no fault of the owner or the maintenance schedule. If there’s a pattern of failure, such as timing chains that stretch or snap on low-mileage and well-maintained cars, then the manufacturer may offer a programme of extended support beyond the original warranty.
This is not the same as a recall or even a technical service bulletin, which will make modifications or corrections at no cost to the owner for safety or reliability reasons. There’s no guarantee that the manufacturer will do anything about the problem in every case, but if there is strong data that says the car has been looked after properly and has failed prematurely, the manufacturer may allow the dealer to repair it and make a contribution to the cost, up to covering it fully.
For example, the 1.5-litre diesel engines found in many Citroen, Peugeot and Vauxhall models made between 2019 and 2022 have weak timing chains between the camshafts. If your five-year old, 36,000 mile example has a catastrophic engine failure, so long as it’s been serviced correctly by a main dealer and is otherwise well looked after, the replacement engine may well be covered or at least a good percentage of the work discounted as goodwill.
If you haven’t kept up with servicing, the chances of this cover being provided are very unlikely. Even if there is a known issue with the part that has failed.
Modern service intervals and component cost-cutting mean lubricants and parts are pushed to the limit. Timing belts and chains have been the most obvious source of issues, but there are thousands of components including digital dashboard displays, seats and bodywork seals that might fail prematurely and be replaced free for those owners who kept servicing the car to manufacturers' specifications or at a main dealer.
What kind of DIY servicing is possible?
The type of home servicing you can do depends on your available space to work in, your physical strength and mobility, plus how much you are willing and able to invest in tools. Some jobs may also depend on your patience and organisation skills.
While this article focuses on mechanical servicing, the first thing you should invest in for any car made after 2001 is a code reader or diagnostic computer. There are many options available and on a basic level they're often useful for resetting the service indicator, but the right level of laptop can be used to recode modules and replacement parts, or calibrate systems.
Less than £200 will get either a powerful secondhand Windows laptop and compatible lead and software, or an easy-to-use self-contained tablet computer dedicated to diagnostics. You can get basic code readers and reset tools for £20, which are usually enough for simpler cars with manual gearboxes.
Diagnostic charges when the car seems fine but is showing a warning light are one of the highest costs you'll pay at many main dealers for lowest return. You do need to take time and learn your car's traits before leaping to replacement parts. Owners' clubs and forums, such as HonestJohn.co.uk's, will have other people who have gone down that road before.
Easy jobs to do at home include:
- Engine oil and filter change (when accessible from above)
- Spark plug change on small and medium petrol-engined cars
- Coolant change
- Replacement of basic radio and speakers
- Lubrication of locks and hinges
- Replacement of bulbs and wiper blades
- Replacement or restoration of lights and lenses
More advanced jobs, needing better access or sophisticated tools, can include:
- Replacement of serpentine/auxiliary belt
- Replacement of tensioners and bearings
- Replacement belt-driven pump or alternator, excluding air conditioning
- Manual gearbox oil change
- Brake pads and discs for routine wear
Move beyond those tasks and you’re getting into the scope of workshops and experience or training as a mechanic. If you want to learn, there are plenty of local colleges and community centres that will help you get hands-on education and experience, rather than watching a YouTube video of someone talking over a wonky camera angle of an engine.
What tools do I need and what will they cost?
An investment of £200 will get a basic set of tools to cover most servicing needs, though you will often come across special fasteners or clips that are much easier to deal with if you buy the right gadget.
- Professional socket set — around £80-£160
- Pela pump — around £50
- Torx and hex bits with screwdriver — around £40
- A torque wrench and a deep spark plug socket for some cars — £40-£100
- For cars after 2001, an OBD-II code reader — from £20
For more advanced jobs, you will want a good trolley jack and set of axle stands, which should cost around £100, plus you may need pry bars or similar tools. Working on suspension parts is within the scope of experienced DIY mechanics but has a high risk factor.
Tool brands do matter but you don’t necessarily need the most expensive. Halfords often offers discounts or promotions on the Professional tool range which have a lifetime warranty. They’re strong and genuinely usable, whereas some of the cheapest options on Amazon are really not worth the money or effort invested in reading the product descriptions.
Secondhand tools make sense for simple castings and sockets that you can inspect for cracks, but are generally a bad idea for anything that requires batteries or will have been struck with a hammer. We’d also be wary of secondhand vehicle lifting tools, particularly unbranded hydraulic jacks or scissor lifts.
How do you change oil without making a mess?
One of the greatest innovations in car servicing is changing the oil from above. Nearly all cars will allow this, though some are designed specifically for it and place the oil filter so it can be changed easily as well. Mercedes set the benchmark here, making it possible to change the oil in twenty minutes. Now you understand how those cheap packages can be offered when the labour rate is over £100 per hour.
Before starting, check the current oil level. If it is above the fill line it may have been overfilled, or there may be another issue. Does it smell of fuel? Diesel cars in particular can dump excess fuel into the engine oil during DPF regeneration, diluting it in the process. This is a sign that there may be an issue with the emissions system if the oil has been changed recently. In this case, don't replace the oil with the same amount that you removed, check the dipstick after three litres or the manufacturer specified amount and refill slowly.
The tool you need is a Pela — or a vacuum — pump. You can get electric versions but they’re no faster and can be more hassle to use. The vacuum pump looks like a garden weed sprayer bottle but works in reverse — simply remove the oil cap, slacken off the filter housing, then take the dipstick out of the car.
Top tip: place the dipstick across the engine, where you can see it from the driver’s seat. It’s a good reminder that it's out if you’re interrupted while working.
Put the vacuum pipe into the dipstick tube, pump the handle, and wait. Warm oil drains faster, same as when changing the traditional way, but it will extract most of a four-litre change in less than half an hour.
Check the amount of oil removed, change the filter (often a cartridge in a plastic housing, plus remember to change the O-rings, clean inside the filter housing while being careful not to crush the filter when refitting) and replenish to the manufacturer's recommended maximum via the filler cap.
Check the level is at least halfway between the marks before starting, as around 500ml will be taken to refill the filter. Switch off, look for leaks, give the oil around 15 minutes to drain back to the sump then check the level again and top up.
Does DIY servicing invalidate breakdown cover?
No. If you have third-party breakdown cover such as Green Flag, AA or RAC, or provided by your insurance company, they do not look at your car's service history. However, they do look at the car to check it's in roadworthy condition, as well as having a valid MOT and road tax.
Although a car should be maintained in good working order, maintaining the service history is not a legal requirement, nor is it part of the MOT. This may change for future emissions standards, as one of the assumptions made is that the emissions level will degrade over the reasonable life of the vehicle.
What can go wrong with DIY servicing?
Most issues with home maintenance come from a lack of experience or sympathy for engineering, such as crossed or stripped threads, such as forcing a spark plug into the hole at the wrong angle or using too much force on an alloy engine. This can also be a problem if someone's done it before and bodged it, then you uncover their actions later.
Even if a car needs physical strength to undo parts, you should be gentle when threading bolts until they are seated. Look up torque specifications — and use a torque wrench — to make sure you don’t over-tighten things like spark plugs or glow plugs.
Mixing up coolant types is an easy mistake that can cause serious problems. There are several formulations, not all of which can be mixed. Blue coolant should not be topped up with red coolant, or vice-versa, as the two formulations react to form a jelly-like gunk that blocks pipes, radiators and the car’s heater.
If the coolant in your car is dirty or very diluted you should flush the system before refilling it. This may reveal other problems on older cars, such as leaking hoses.
Ordering parts can prove tricky — try and use a local motor factor first and use your car’s VIN to check that the parts suggested are correct. There’re few things as frustrating as being halfway into a job and realising the parts you waited 10 days to travel across Europe are wrong, meaning you need to wait another 10 to send them back for replacements.
While changing fluids such as oil and coolant is generally straightforward, brake fluid is another matter. On most old cars the bleed nipples on the brakes will rust into the calipers and break off, meaning you can’t get air out of the system. Fixing this means drilling out the broken part and cleaning up the caliper and often leads to replacing more of the braking system than you'd intended.
We’d leave changing brake fluid to a workshop that’s seen it all before, over trying it at home with no previous experience. Most formulations of brake fluid will also do serious damage to your car's paintwork if spilled or splashed onto it.
How safe is working on your own car?
- Never work underneath a car that isn't properly supported
- Before working on electrical parts, disconnect the battery's negative lead
- Petrol fumes are flammable, oil is carcinogenic if not washed off
Most failures are merely inconvenient but the worst examples of what can go wrong with home servicing are those that put your own safety in jeopardy.
Any job that involves working underneath the car with jacks, axle stands or cheap ramps has the potential to cause serious or even fatal injury. Do not rely on a factory jack or just a single support. Cars are heavy and unstable when supported by jacks that are designed for wheel changing.
If you want to work on brakes, suspension, the exhaust or just cleaning and rustproofing underneath your car, always make sure it has enough support so if a stand or jack fails it won’t land on you. Even putting the removed wheels under the sills could mean only the car, rather than your body, gets damaged, but it's better to invest in proper supports. If you only need them for one job check out local tool hire companies or repair shack-type community projects to see if you can hire some.
When working on fuel-related or electrical systems, disconnect the battery — or remove it entirely. It's remarkably easy to accidentally bridge the connections, causing a spark that could ignite fumes. You should also disconnect the battery when working on interior parts with airbags and when welding.
Never work in an enclosed space with poor ventilation, even if you don't plan on running the engine. Parts cleaners, petrol vapour and other fumes can cause dizziness and disorientation. If you're sanding or wire brushing rusty or painted parts, wear a dust filtration mask and goggles. When you're working on a dirty engine use barrier cream and gloves to avoid getting too much oil on your skin.
Environmental responsibility and DIY servicing
Most things that come out of a car are not good for the environment, but ethylene glycol antifreeze — that's the blue-green, sweet-smelling type — is very toxic to wildlife and pets. Rinse any spills thoroughly and don't leave uncovered drip trays to capture it unattended. Small quantities can be disposed of down the toilet, where they will be processed by sewage facilities but shouldn't be poured into rainwater drains or soakaways.
Some car parts, particularly friction surfaces such as brake pads and clutches, contain asbestos. Wear gloves and a mask when handling them and be sure to bag and seal any parts removed.
Drawbacks of servicing your car yourself
As we've covered, it's relatively easy to change oil, filters and basic service items yourself and save money in the process. For cars without special oil requirements, you can get reasonable-quality 10W40 for as little as £17 for five litres.
However, you have to dispose of whatever you have removed. Oil should be captured in a container — if you still have new oil in the bottle you've filled you engine from, then an an old screen wash bottle is usually big enough for a five-litre change. Most household recycling centres have facilities for disposing of engine oil. It's usually filthy, so remember to wear disposable gloves and take some hand wipes before you get back into your car.
Items such as wiper blades and spark plugs will end up in scrap metal or general waste at the recycling centre. Car batteries can also be recycled but some scrapyards will pay for them, while Halfords will dispose of a battery for you.
Cleaning up oil spills isn't fun but it's preferable to cleaning up pets that have run through them. A good, stable drain pan of the enclosed type is best if you're not using a vacuum pump.
Finding parts online has become harder, thanks to excessing spamming of search terms by the likes of PartEx, which operates under different brand names. Motor factors have become more expensive, unable to compete with online sellers — perhaps surprisingly, it may be worth talking to Halfords. They don't carry items in stock, but can order them in.
On newer cars, buyers and dealers may not be happy with a history of DIY servicing unless it's very well documented and backed up with receipts for parts and ideally exceeding the manufacturers' minimum standards.
