- Underneath the car, near the front of the engine oil pan.
Mercedes-Benz C-Class with 1.8L Kompressor Engine:
- Underneath the car, about halfway up the oil pan.
- It's a silver plug with a 19mm bolt head.
Mercedes-Benz C-Class with 3.2L V6 Engine:
- Underneath the car, about halfway up the oil pan.
- It's a silver plug with an Allen head.