Oil leaks in a 2017 Mercedes-Benz C-Class can be caused by several factors. Understanding these causes is essential to properly diagnose and fix the issue. Below, you will find all potential causes and solutions broken down in detail.

 
Common Causes of Oil Leaks
 

• Faulty Oil Filter: One of the most common causes is a faulty oil filter. The oil filter can become damaged or improperly installed, leading to oil leakage.
• Worn Gaskets or Seals: Over time, gaskets and seals, such as the valve cover gasket, oil pan gasket, or crankshaft seals, can wear out, resulting in leaks as they fail to contain the oil within the engine.
• Damaged Oil Pan: The oil pan is exposed to road debris which can occasionally strike the oil pan, causing it to become damaged or punctured, leading to leaks.
• Loose or Damaged Drain Plug: The oil drain plug may loosen over time or become damaged due to improper removal or installation, causing an oil leak.
• Crankshaft or Camshaft Seals: These seals can wear out or get damaged over time, leading to leaks. Crankshaft and camshaft seals are crucial for preventing oil from leaking out where rotating parts pass through the engine block.
• PCV Valve Issues: A faulty Positive Crankcase Ventilation (PCV) valve can lead to increased pressure within the engine, causing seals and gaskets to fail and leak oil.
• Head Gasket Failure: Though less frequent, a head gasket failure can lead to oil leaks. This is often associated with other symptoms such as coolant leaks, smoke from the exhaust, or engine overheating.

 
Fixing Oil Leaks
 

• Replace Faulty Oil Filters: Ensure the oil filter is correctly installed and replace it if it shows signs of damage or improper sealing.
• Inspect and Replace Gaskets and Seals: Perform regular inspections and replace any worn or damaged valve cover gaskets, oil pan gaskets, or crankshaft seals. Make sure replacements are done using quality parts to ensure a good seal.
• Repair or Replace the Oil Pan: Inspect the oil pan for any signs of damage. Depending on the extent of the damage, the oil pan may need to be repaired or replaced.
• Tighten or Replace Drain Plug: Check the drain plug for any signs of wear or damage. Tighten it properly if it's loose, or replace it if needed.
• Replace Crankshaft or Camshaft Seals: If these seals are the source of the leak, they will need to be replaced. This can be a labor-intensive process, so professional service is often recommended.
• Address PCV Valve Issues: If a faulty PCV valve is identified, cleaning or replacing the valve might resolve the issue. Ensuring proper ventilation to relieve pressure in the engine can prevent future leaks.
• Identify and Repair Head Gasket Leaks: If the head gasket is failing, this may require significant engine work to replace. It is advisable to consult a professional mechanic due to the complexity of the repair.

In all cases of dealing with oil leaks, regular maintenance and routine inspections are critical in preventing leaks before they cause more significant damage. Periodic checks of engine compartments for oil drips or puddles beneath the car can also help catch leaks early. It's usually recommended to consult a certified mechanic for diagnosing and fixing oil leaks, particularly for intricate procedures like replacing crankshaft seals or head gaskets.