should you check oil levels when engine is hot or cold?

Either, when the motor is hot check the oil AFTER the motor has been off for about 5 minutes. This allows plenty of time for the oil that circulates in a running motor to drip down into the oil pan. If you wait the 5 minutes you get an accurate reading either way, providing the vehicle is sitting on level ground.

The proper technique for a hot motor is pull the dip stick, wipe it dry, insert it completely, pull it again and then look for your level to get an accurate reading. When cold you can just pull the dipstick, read it and reinsert it.

…and, be sure that it is parked on level ground when checking the oil level.

Agree with above posters; you should NEVER check the oil after starting it up from very cold and then shutting it off a moment later. That will give a low level reading since the oil is still up in the top part of the engine.

I normally check the oil before starting up the engine in the morning; that gives the most accurate reading.

It doesn’t really matter that much. You can check it when it is hot or cold. Just be careful not to burn your hand on a hot dip stick.

Some owner’s manuals say to check it when it is hot, and some say to check it when it is cold.

The way I look at it, it is like checking your tire pressure. It is best to check your tires when then are cold, but if wait for them to be cold to check them, you might forget. In this case, it is better to check then when they are hot than not check them at all because you (I) forgot to do it when they were cold.

Check it when the oil has time to drain into the sump. This could be before you start the engine in the morning, or a couple of hours after you return home in the evening.

I’d also add that it’s only thanks to the miracle of the plastic handled dipstick that you can check the oil hot without burning yourself.