The sensor is not very precise, as it is a float riding in a 2+ gallon capacity oil pan, subject to sloshing. It's amazing that it works as well as it does, when it does. It's intended to warn you when the level is low, not to determine the exact oil level. On some trucks it will start to flicker or light up if the oil is not even a quart low, and in others it might not indicate anything until it's several quarts low. I pay attention to my dipstick when I do oil changes and after every run, and my truck will burn/leak a quart every 500-800 miles. A quart low barely registers on the dipstick, and many people wouldn't bother to add oil until the level is towards the bottom of the hashed area- but at that point it's lost a lot more than they realize, IMO. Do you measure how much oil you get out of the pan when you change the oil? I do, which is how I have a good idea of how low it is based on the dipstick. If you don't measure how much you get out, you might want to once- you might be surprised at how low you really are after 5000 miles. And your light may not work at all, that's very common. On the other hand, maybe your truck really only uses a quart per oil change, what the hell do I know? I'm just trying to help people who don't understand what the oil level light is telling them, and to understand how it works.