Oil tank

Cars do not exactly have an "oil tank". They have an oil pan on the bottom of the engine that holds the oil, but you would need to open the hood to remove the fill cap. Most engines have a baffle right under that cap, so debris might not even be able to get to where it would do damage.

If you meant to say "gas tank", do not even worry about screws there. All fuel pumps sit inside a small bowl in the tank, and screws will not get into that. Then there is a screen on the pick-up tube that will prevent debris from entering the fuel pump.