If your car is low on oil, you may be tempted to just add some to the dipstick hole. But this isn't the best way to add oil to your car. The dipstick hole is actually for checking the oil level, not for adding oil. If you add oil through the dipstick hole, it can drip down into the engine and cause damage. It's better to add oil through the fill cap or funnel so that it goes right into the engine.