How to check oil in a car

Checking oil in your carWhy do you need to check oil in your engine? Engine oil has two functions: it lubricates moving parts and helps to dissipate the heat produced by combustion. The lubrication function is especially important. For example, the crankshaft, which is the engine main rotating part, makes on average 3.1 million revolutions per month of driving, yet it is only separated from the non-moving parts by a very thin layer of oil (around 0.0012 in or 0.03 mm) that is supplied under pressure. Oil also lubricates pistons moving up and down in the cylinders as well as all other moving parts of the engine. To work properly, the engine must be filled with the proper level of oil. Normally, the engine consumes some amount of oil, so the oil level drops over time. As the oil level drops, oil quality deteriorates faster causing increased friction and wear. By checking the oil level, you can catch if it’s low and top it up if needed. You also can see how dirty is your oil – see the examples below.
First check the owner’s manual, it contains the safety precautions as well as the proper way to measure the oil level in your car. Here, we used the V6 Toyota Camry as an example.
To check the oil level, warm up the car, park it on a level spot, shut the engine off and wait for a couple of minutes to let the oil drain down into the oil pan at the bottom of the engine.

Engine oil dipstickOpen the hood and locate the engine oil dipstick; in most newer cars it has a yellow handle that says ‘Engine Oil’. Your owner’s manual has a map of the engine compartment within the ‘Do-It-Yourself Maintenance’ section. The oil dipstick and the oil filler cap are marked on this map.
Checking engine oilPull the dipstick out. Be careful, some parts of the engine could be hot. Hold the rag or towel under the lower end of the dipstick so the oil won’t drip onto the engine.
Checking engine oilWipe the dipstick with a clean rag or paper towel.
Checking engine oilInsert the dipstick back into the dipstick tube until it’s fully seated.
Engine oil levelPull the dipstick out again and check the oil level – it should be between ‘Low’ and ‘Full’ marks. In some cars, a dipstick has a cross section  instead of marks; in this case, the level should be within the cross section. Once again, if in doubt, your owner’s manual has a picture how it looks like. Once you done, make sure to replace the dipstick into its place.

How to read the oil dipstick. Examples:

Oil level on the dipstickIn this car, oil looks clean and the oil level is FULL.  Good job; keep driving.
Dirty oil in a car engineHere, the level is okay, but  oil looks dirty. It’s a good idea to have the oil change done.
Low oil level, dirty oilThis oil is very dirty and the level is below the LOW mark. It’s time to change your oil.
Low oil level in a carThis oil looks a bit dirty and the level is low. You may want to add some engine oil to bring it to the proper level. If it’s been a while since your last oil change, consider booking an appointment for your next oil change. Oil filler capTo top up, use the same grade oil as you already have in the engine. The required oil grade (e.g. 5W-20, 0W-20 or 5W-30) is usually  marked on the engine oil cap or you can find it in your owner’s manual. Make sure to use synthetic oil if the owner’s manual specifies so. In most cases, the owner’s manual has the reference how much oil needs to be added to bring the level from ‘Low’ to ‘Full’. Adding oil to the car engineFor example, in this V6 Toyota Camry, it takes 1.6 qt or 1.5 liters, according to the manual, to bring the level from ‘Low’ to ‘Full’. When adding oil, add a small amount, let it drain down, then recheck the level. If it’s still low, repeat; but don’t overfill. Use a funnel to avoid spills.
Another option is to visit your dealer or repair shop and have them top up your oil for you.

By Testing Autos Editors.