Why is My Car Leaking Oil When Parked?

If you’ve noticed a puddle of oil forming under your car after it’s been parked for a while, it’s a sign that you have an oil leak. While oil leaks can sometimes be minor, they should never be ignored as they can lead to engine damage if the leak worsens over time.

Common Causes of Oil Leaks When Parked

There are several potential causes for an oil leak that appears when your car is parked:

1. Worn Oil Filter Gasket The oil filter gasket seals the filter to the engine block. Over time and due to heat cycles, this gasket can dry out and crack, allowing oil to seep out.
2. Leaking Oil Pan Gasket The oil pan gasket seals the oil pan to the engine block. This gasket can deteriorate from age, causing oil to leak out onto the ground when parked.
3. Damaged Oil Pan Drain Plug The drain plug seals the opening where oil drains from the oil pan during changes. If overtightened or stripped, the drain plug can allow oil to escape.
4. Leaking Valve Cover Gaskets Valve cover gaskets seal the valve covers to the cylinder heads. When these gaskets age and crack, oil can seep out around the top of the engine.
5. Bad Front/Rear Main Seals The front and rear main seals prevent oil from leaking out where the crankshaft exits the engine block. Worn seals cause leaks.
6. Aging Oil Pressure Sensor/Switch The oil pressure sensor or switch can weep oil from its housing as it gets older, leaving a thin trail of fresh oil puddles.

Diagnosis and Repair

To pinpoint the source of your leak, your mechanic will perform a visual inspection looking for telltale signs and staining patterns. For harder to detect leaks, dye may be added to the oil, or a smoke test performed.

Once the source is found, the related gasket, seal or component will need to be replaced to stop the leak. Repairing oil leaks sooner rather than later prevents excessive oil loss which can lead to engine damage.

Also Read:

• What is the Check Engine Light and Why is it On?
• Resetting Your Car’s Computer After a Battery Change: What You Need to Know
• How Long Does It Take to Change Brake Pads?
• The Real Cost of Transmission Service in the United States

If your car is leaking oil when parked, have it inspected promptly. While repairing the leak has a cost, it’s far less expensive than the potential price of an oil-starved engine failure down the road.