Engine oil is used to reduce friction between parts and keep your engine running smoothly. Low oil levels or contaminated oil can cause severe damages to your engine that can be difficult or expensive to fix, and may leave lasting ticking sounds that may never go away. You should check your oil at least once a month to ensure that it hasn't become dirty and to keep an eye on the amount left.
When you check oil, make sure the engine is cold by turning off the vehicle and waiting at least ten minutes. Then, pull out the oil dipstick and wipe it with a lint-free rag, put it back in, and pull it out again. This will give you an accurate reading of how high the oil comes on the dipstick, in addition to giving you a look at the film of oil on the stick itself so you can check if it has become dark or dirty. If oil levels are low, you can easily fix this problem by adding more.
When adding oil to the engine, don't add it directly to the small hole the dipstick sits inside. Instead, look for a large screwed-on cap nearby. All you have to do is unscrew this cap, pour oil inside until it's to a reasonable level, and then replace the cap. If you need to change your oil, all you have to do is let the old oil drain out of the oil drain plug before pouring in the new oil. Once that's done, the process is over, and you have clean, shiny, healthy levels of oil in your engine.