A guide to oil maintenance in your car

Q: What does it mean when the oil light turns on?

If your oil warning light comes on, it could mean you’re low on oil or even that your engine is overheating. While this doesn’t necessarily mean your car is unsafe to drive, you should pull over as soon as possible and check your oil levels. If in doubt, call a mechanic.

Oil helps to cool your engine and keep your car’s inner workings from seizing up. Here’s how to check your vehicle’s oil, spot problems and get an oil change when you need one.

Written by

Rory Reid

Car and technology expert

Last Updated

7 SEPTEMBER 2022

4 min read

Why do cars need oil?

Oil keeps your car’s engine running smoothly. Without it, everything can quickly grind to a noisy, damaging halt.

The moving parts inside the engine need oil to minimise friction and keep temperatures low. Otherwise, metal surfaces such as the engine pistons grind against each other and generate heat. Without oil they’ll seize up, marking the end of your engine and your motoring adventures in that car.

Motor oil isn’t just a lubricant though. It contains chemicals that keep viscosity levels just right, reduce corrosion and help clean the car’s system.

Every vehicle has its own oil requirements, and what’s right for one might be harmful to another. So if you’re buying oil, always check your manual to find out what type is best.

Changing your oil

Most cars need an oil change every 12,000 miles or every 12 months – whichever comes first. This prevents dirt and grit build-up, which can cause engine damage in both petrol and diesel cars. But if you’re using long-life oil, you may be able to go around double that distance or time without an oil change, depending on how you drive the car. If you’re not sure when yours is due, check with your car’s manufacturer or your usual garage.

Although you can change the oil yourself, it can be pretty messy and involves getting underneath the car to drain the old oil away. You’ll also need to safely dispose of it at a recycling site. So, for many people, having an oil change as part of a regular service is the easiest, cleanest solution.

Spotting oil-related problems

There are a few tell-tale signs of an oil problem:

The oil warning light comes on. If the oil can-shaped warning light stays on once you start the car or comes on while you’re driving, switch off the engine and get help from a mechanic. If you keep driving, you could cause serious engine damage. If you’re on a motorway, stop at the next services.
There’s oil on your drive. Patches of oil where your car was parked are never normal. This indicates an oil leak somewhere and should be checked ASAP.

How to check your oil

It’s pretty easy to check your car’s oil level and make sure everything’s working smoothly. You should do this every few weeks, and always before going on a big road trip. Check the oil when the engine is cold, and with the car parked on level ground. Here’s how to do it:

Get some kitchen roll or an old cloth, then open the bonnet and find the dipstick. It’s normally a metal stick with a small finger-sized yellow ring on the end (your manual will help if it’s not obvious)
Remove the dipstick and wipe it clean. You’ll see it has ‘MIN’ and ‘MAX’ markers towards the tip of the stick
Replace the dipstick and leave for a few seconds
Remove it again and look at where the oil comes up to. If it’s between ‘MIN’ and ‘MAX’, you’re good to go. MIN means you’ll have to top up with the appropriate oil. If it’s significantly above the MAX marker then head to a garage to get the level adjusted.

How to top up engine oil

If your car’s oil level is looking a bit low, you can top it up yourself by pouring more in through the oil filler cap. You’ll usually find this next to the dipstick. Add a little, check the level, and then keep adding more until it’s just right.

If you find you’re needing to top up the oil regularly, you may have a leak, in which case it’s a good idea to get your car checked by a mechanic.

Do electric cars use oil?

Electric cars (EVs) don’t use engine oil, but some use lubricants in their transmission. Whether this needs to be checked and/or changed will depend on the model. If you have an EV, look in the handbook to see what needs to be done but it’s not generally something you need to worry about.

Do hybrid cars use oil?

Even though they’re partly electric, hybrid cars have an internal combustion engine, so they still need oil changes – just as a purely petrol or diesel car does. This includes plug-in hybrids – even if you run them mostly on electric power.

Frequently asked questions

How often should I change engine oil?

How often you’ll need to change your engine oil will depend on what type of vehicle you drive. Rather than waiting for your dashboard light to come on, it’s better to check your handbook to see exactly what’s required.

Does an engine oil and filter change count as a service?

A service is a check of your car’s mechanical and electrical parts. An engine oil and filter change might be included, but it’s not the same thing.

When should I check my oil level?

You should check your oil levels when the engine is cool. If you get into the habit of doing it every few weeks, it’ll start to come naturally.

What is oil viscosity and what impact does this have on my engine?

Viscosity refers to how easily your oil pours. Thicker oils have a higher viscosity than thinner ones, which can make them harder to pour in cold weather. If an oil is too thick, it may mean the engine has to work harder – making it more difficult to start. Consult your car’s manual to know which oil is right for you.

What does it mean when the oil light turns on?

If your oil warning light comes on, it could mean you’re low on oil or even that your engine is overheating. While this doesn’t necessarily mean your car is unsafe to drive, you should pull over as soon as possible and check your oil levels. If in doubt, call a mechanic.

How much is an oil change?

How much you pay to have your oil changed will depend on where you live and what type of vehicle you drive. Garages tend to base their prices on your engine size and what type of oil you need. Synthetic or specialist oils often cost more but won’t need to be changed as often.