How to check your engine oil (and top it up)
By James Snow
Owner and mechanic, SV Autos
Updated 25 July 2026
Oil is the one thing your engine can't run without for long, and a car that's low on oil can do itself expensive damage in a very short space of time. Checking it takes two minutes and needs no tools, so it's worth doing every few weeks and before any long drive. Here's how to check it properly and top it up without making a mess of it.
Why the oil level matters so much
Engine oil keeps all the moving metal parts lubricated and cool. Run low and those parts start wearing against each other, which at best shortens the engine's life and at worst wrecks it. Modern engines can use a bit of oil between services, which is normal, so a quick check now and then is the cheapest insurance you'll ever buy.
If the oil warning light (a red or orange oilcan symbol) ever comes on while you're driving, that's not a check-when-you-can light. Stop as soon as it's safe and check the level, because low oil pressure can destroy an engine in minutes.
Do it cold and on level ground
For an accurate reading the car needs to be parked on flat ground with the engine off. Check it cold, before you set off, or leave a warm engine to stand for ten minutes so the oil drains back down into the sump. Checking it on a slope or straight after a drive gives you a false reading.
Find the dipstick and read the level
Open the bonnet and find the dipstick, usually a loop or a brightly coloured (often yellow) handle sticking out of the engine. Some newer cars have no dipstick and show the level on the dashboard instead, in which case follow the car's menu.
Pull the dipstick right out, wipe it clean with a rag or kitchen roll, push it fully back in, then pull it out again and look at the film of oil on the end. There are two marks, a minimum and a maximum. You want the oil sitting between them, ideally near the top mark.
- Below the minimum mark: top it up before driving
- Between the marks: you're fine, near the top is best
- Above the maximum: too much oil, which can also cause problems, so get it looked at
Topping it up
Use the oil grade your car's handbook specifies, it's usually printed on the oil cap or in the manual. Using the wrong grade can affect how the engine runs, so it's worth getting right.
Unscrew the oil filler cap (marked with an oilcan symbol, not the dipstick), and add a little at a time, maybe 100 to 200ml, then wait a minute and re-check with the dipstick. It's much easier to add more than to take excess out, so go slowly and don't overfill past the maximum mark.
When to stop and get help
If the oil is very dark and gritty, milky or mayonnaise-like, or the level keeps dropping quickly, don't just keep topping it up, those are signs of a problem worth getting looked at. The same goes for any oil warning light that stays on with a healthy level, or oil pooling under the car.
If checking or topping up isn't your thing, that's completely fine. A proper oil and filter change resets everything to clean oil at the right level, and we can do it on your driveway.