The correct and safe way to check your engine oil level is always with the car turned off and parked on a level surface. For the most accurate reading, you should also wait a few minutes after turning off the engine to allow the oil that’s circulating up in the engine to drain back down into the oil pan.
Checking the oil while the engine is running is dangerous and will give you a false, low reading. When the engine is on, the oil pump is actively circulating oil throughout the engine block, meaning there's significantly less oil sitting in the pan where the dipstick measures it. This can cause you to overfill the oil if you add more based on an incorrect reading. Overfilling can lead to excessive pressure, foaming, and serious damage to engine seals and components.
Checking Oil with Engine Off vs. On
| Factor | Engine OFF (Correct) | Engine ON (Incorrect) |
|---|
| Oil Location | Drained in the oil pan for accurate measurement | Circulating through the engine; pan level is low |
| Reading Accuracy | High and reliable | Falsely low, leading to overfill risk |
| Safety | Safe; no moving parts | Dangerous; hot, moving engine components |
| Procedure | Standard and recommended by all manufacturers | Not recommended and hazardous |
Here’s the simple process for an accurate check:
- Park your car on a flat, level surface and turn off the engine.
- Open the hood and locate the dipstick (usually has a bright yellow or orange handle).
- Pull the dipstick out completely and wipe it clean with a rag or paper towel.
- Re-insert the dipstick all the way back into its tube, then pull it out again.
- Look at the end of the dipstick. The oil level should be between the two marks or holes labeled "MIN" and "MAX" or "FULL." If it's near or below the MIN mark, you need to add a quart of the recommended oil type.
