Car basics · First steps · about 5 minutes
Check Your Engine Oil
Engine oil keeps the moving metal parts inside your engine from grinding against each other. Checking it takes a few minutes and a clean rag. Too little oil can cause major engine damage, so this is a good habit to learn early.
When to teach it: Watch from about 8, help from about 10, do it alone from about 13 with an adult nearby the first few times.
You'll need
- Your car's owner's manual
- A clean rag or paper towel
- The motor oil your car needs, if you have to add some (look on the oil fill cap or in the owner's manual)
- A funnel
Before you start
- Park on level ground so the reading is accurate.
- Turn the engine off. Checking with a cold engine keeps your hands away from hot parts.
- Keep your hands off the radiator hose and other engine parts, which can be hot after driving.
Step by step
Tick each step as you go if you like; ticks stay on this device.
Physics
How it works: Why engines need a slippery film
When two surfaces rub, friction pushes back against the motion. Inside an engine, metal parts slide and spin past each other the whole time it runs. Motor oil spreads a thin protective layer between them so they don't scrape and collide. It also helps keep the engine from overheating.
Viscosity means how much a liquid resists flowing. Honey has high viscosity. Water has low viscosity. Oil gets thicker when it's cold and thinner when it's hot.
A label like “5W-30” gives two ratings. The number before the W is the cold-weather rating: a lower number means the oil flows more easily when the engine is cold. The number after the dash tells how thick the oil is once the engine is warmed up. Thinner oil flows easily but makes a thinner protective film, so your engine is designed for one grade. Use the one on the oil fill cap or in your owner's manual.
friction force = μ × N (μ is how “grippy” two surfaces are; N is how hard they press together)
Try it: Put a spoonful of honey from the fridge on one plate and a spoonful of room-temperature honey on another. Tilt both plates the same amount and watch them race. The cold honey has higher viscosity, so it creeps slower, just like cold engine oil.
Keep learning: Science
Teaching it to your kids
- Let your child pull and wipe the dipstick while you watch.
- Ask them to read the level out loud: below the low mark, between the marks, or at full.
- Show them where the oil grade is printed on the cap or in the manual.
- Pair the check with a regular errand, like getting gas, so it becomes a habit.
Tips
- Look for the recommended oil grade on the oil fill cap. If it isn't there, check the owner's manual.
- Wipe around the dipstick and oil cap before opening so dirt doesn't fall in.
- Use a clean cloth on the dipstick. Grit on it can get into the engine.
- Keep a quart of the right oil at home so you can top off when you need to.
Common mistakes
| Mistake | Instead |
|---|---|
| Reading the dipstick on the first pull | Wipe it, push it all the way back in, and read the second pull. |
| Checking on a hill or slope | Park on level ground so the oil sits evenly in the engine. |
| Overfilling | Add a little at a time and recheck. Stop at the upper mark. |
| Using whatever oil is on the shelf | Use only the type your owner's manual lists. |
Safe habits
- Check with the engine off.
- Keep your hands away from hot engine parts like the radiator hose.
- Wash your hands with soap and warm water after touching used oil.
When to call a pro
- If you have to add oil often, have a repair shop check the car.
- If the red oil pressure warning light comes on, see the dashboard warning lights guide and have the car checked.
Sources
Free how-to guides for families, with nothing to earn, pass or send in. They follow U.S. rules and sources; your owner's manual, product labels and state and local rules come first.