Oil is the only thing standing between your engine’s moving parts and each other. Running low does not announce itself politely, and by the time an engine sounds unhappy the damage is usually done. A check takes two minutes, needs no tools, and is the single most useful habit a car owner can build.
Do it once a month, and always before a long drive.
Before you start
- Park on level ground. A slope tips the sump and gives you a false reading, which is the most common reason people misjudge their oil.
- Switch the engine off and wait. Oil needs time to drain back down into the sump, and five to ten minutes is the usual advice.
- Check whether your car wants the engine cold or warm. Most manufacturers specify one or the other, and a few specify a warm engine at idle. Your manual settles it.
- Have a clean rag or paper towel ready.
Finding the dipstick
The dipstick handle is usually a brightly coloured loop or T-grip near the top of the engine, often yellow or orange. If you cannot find it, the engine bay diagram in your owner’s manual shows exactly where it sits.
Some cars do not have one. A growing number of engines use an electronic oil level sensor instead, and you read the level through the driver’s display menu rather than under the bonnet. If there is no dipstick, do not go hunting for one — check the instrument cluster menus, and your manual will tell you which one.
Reading the level
- Pull the dipstick out fully and wipe it clean along its length.
- Push it all the way back in, until the handle seats properly. This step is what makes the reading accurate.
- Pull it out again and hold it horizontally, so oil does not run along it.
- Look at the film of oil against the two marks near the tip. They may be labelled MIN and MAX, they may be two notches, dots or a crosshatched zone.
- The oil should sit between the two marks. Anywhere in that band is fine. Near the upper mark is ideal.
If the level sits at or below the lower mark, top up before driving.
Topping up
- Use the exact oil grade your manual specifies. The grade is a code such as 5W-30, and it is not interchangeable advice — it is an engineering requirement tied to your engine’s clearances and your climate.
- Add a small amount at a time, perhaps 200 to 300 ml, then wait a minute and re-check. The gap between the two marks is often around a litre, so it is easy to overshoot.
- Never fill above the upper mark. Overfilling can let the crankshaft whip the oil into foam, which does not lubricate, and it can force oil into places it should not go.
- Refit the filler cap firmly. A loose cap sprays oil around the engine bay.
Topping up is not the same as an oil change. Fresh oil added to old oil does not reset the service interval.
What the oil itself tells you
- Dark brown or black oil is normal. Oil darkens as it does its job, and colour alone is a poor guide to whether it needs changing. The service schedule decides that.
- Milky, creamy, or the colour of coffee with milk can indicate coolant mixing with the oil. Stop driving and have the car inspected. This one is worth taking seriously.
- A gritty feel between your fingers suggests contamination and is worth mentioning at your next service.
- A level that keeps dropping between checks means the engine is burning or leaking oil. Note roughly how much you add and how far you drove, and tell your mechanic — that figure is genuinely useful to them.
The oil pressure light is not a low oil light
This trips people up constantly. The red oil can symbol warns that oil is not circulating at the pressure the engine needs. It is not a gauge, and it does not come on gently when the level gets low.
If it lights while you are driving, stop safely and switch the engine off straight away. An engine can destroy itself in under a minute without oil pressure. Check the level, and if it looks normal, do not simply restart and carry on — have the car looked at.
Your manual has the final word
Oil grade, oil capacity, whether to check hot or cold, the service interval, and whether your car even has a dipstick all vary between models and engines. Where this guide and your owner’s manual disagree, follow the manual — it was written for your exact car by the people who built it.
