Where is oil sending unit on 1988 4 cylinder Chevy Celebrity?

The oil sending unit on a 1988 Chevy Celebrity 4-cylinder is located on the bottom of the oil pan. It's a small, usually cylindrical, unit with a single wire connected to it. You'll likely need to get under the car to see it. Because it's on the oil pan, be prepared for potential oil spillage when removing or replacing it. Always disconnect the negative battery terminal before working near the electrical components of the engine.