How to Check Engine Oil: Dipstick Steps and Top-Up Guide

Under the bonnet there's one stick of metal that tells you whether your engine is looking after itself. Most drivers know it's there. Fewer know how to read it, and plenty go from one annual service to the next without ever pulling it out.

This guide follows the AA's step by step advice on checking and topping up engine oil, plus the Highway Code's guidance on regular fluid checks. Cars differ, so keep the handbook handy: it'll show where the dipstick sits and which oil your engine needs.

Why checking your engine oil level is worth the few minutes

Oil keeps the moving parts inside the engine lubricated. The AA warns that if the level runs low, metal rubs on metal and can quickly cause irreversible damage. It also says a dashboard oil pressure warning light, especially when cornering, can be a sign the level is too low.

The Highway Code tells drivers to check fluid levels in their vehicle at least weekly. The AA suggests checking the oil every few weeks and before long journeys, rather than waiting for the annual service.

Getting the car ready before you check the oil

A little preparation gives you a reading you can trust. The AA's advice covers the setup:

• Park on level ground. The AA says never to park on a slope, because the reading will be wrong.
• Check the oil before you use the car, when the engine is cold. If you've just been driving, wait 5 to 10 minutes.
• Never try to check anything under the bonnet with the engine running.
• Have kitchen towel, a funnel and a bottle of the correct oil ready, plus gloves if you'd like them.

Using the dipstick: how to read your engine oil level

1. Open the bonnet and look for the brightly coloured plastic handle. If you can't spot it, check the handbook.
2. Pull the dipstick out and wipe it clean with kitchen towel.
3. Push it fully back into its tube, then pull it out again.
4. Read where the oil line sits against the two notches, one for minimum and one for maximum.

Where the oil sits	What the AA says to do
Between the minimum and maximum notches	The level is fine
Below halfway between the notches	Add some oil
Close to or below the minimum notch	Add oil

Some modern cars have no dipstick at all and show the oil level on the dashboard instead, so your handbook will tell you how your car does it.

Topping up engine oil without overfilling it

The AA says the gap between the minimum and maximum notches is about one litre, so a car sitting at or below minimum needs roughly that much. If you're unsure, go slowly.

1. Find the oil filler cap on top of the engine, marked with the word oil or an oil can outline.
2. Take the cap off and pour in a little oil at a time through a funnel.
3. Wait a couple of minutes for the oil to settle, then re-check the dipstick.
4. Stop once the level is between the notches, and refit the cap firmly.

The AA is blunt about the other side of the coin: putting too much oil in is as harmful as having too little.

Choosing the right engine oil for your car

The handbook lists the specification, such as ACEA, API or VW, and the grade, written as numbers separated by a w, like 5w30. The AA warns that using the wrong oil can damage the engine, so don't guess from what a friend uses. If you've lost the handbook, the AA points to the oil-matching tools on oil makers' websites, where you enter your registration or your car's make, model, year, engine and fuel type.

What the colour and texture of your engine oil tell you

The AA explains that new oil looks clean and golden, then darkens to brown or black in use, and that's normal. It can even look black straight after a top-up because it mixes with the old oil. What matters is the texture:

• Black and sludgy: the oil needs replacing.
• Milky, creamy or foamy: the AA says coolant or water may be leaking into the oil, so have a mechanic look at it.

The AA says most cars need an oil change every 9,000 miles or 12 months, whichever comes first, though your handbook gives the maker's interval and some cars tell you when an oil service is due. It also advises topping up before an MOT, as a garage may refuse to test a car if the oil is too low.

Oil checks alongside other car warning signs

Oil isn't the only job worth doing before a long trip. The tyres need attention too, and I've covered how to check tyre pressure in the same step by step style. And if a charging warning appears while you're driving, what the battery light means explains why that one is a red light.

One small tip from the AA's guidance on dashboard warnings: if an engine warning light comes on just after you've checked the oil, make sure the dipstick has been pushed fully home.

Sharing your engine oil know-how with other drivers

If you enjoy explaining how cars work, there are places looking for people who can do it clearly.

If you know cars well, you might want to see automotive sites open to articles from outside writers.

Frequently asked questions

Should I check engine oil when the engine is hot or cold?

The AA says to check before you use the car, when the engine is cold. If you've just driven, wait 5 to 10 minutes first.

How often should I check my engine oil?

The Highway Code says to check fluid levels at least weekly. The AA suggests every few weeks and before long journeys, as a minimum.

How much oil do I add if the dipstick is at the minimum mark?

The AA says the gap between the notches is about one litre. Add oil slowly, wait a couple of minutes, then re-check so you don't overfill.

What does milky engine oil mean?

The AA says milky, creamy or foamy oil can mean coolant or water is leaking into it. Don't ignore it; have a mechanic check the car.

Can I use any oil to top up?

No. Use the specification and grade in your handbook. The AA warns that the wrong oil can damage the engine.