Changing the oil in your engine is one of the most important car maintenance tasks you can perform on your vehicle. However, if oil is leaking out of your engine, it doesn't matter if you are on top of changing the oil in your engine. Your engine is going to get damaged if you don't constantly top off the oil to your engine, figure out where the leak is coming from, and stop the leak.
Leaking oil has a greasy brown look to it. It is very distinctive and will leave behind a stain where your vehicle was parked. There are a few primary reasons your vehicle may be leaking oil.
Reason #1: Bad Valve Seals
Valve seals and rings are usually made from a flexible plastic material, which can get worn down over time. If you have valve seals or rings that have become cracked or damaged, the oil can leak out around the seals. Usually, you will not notice this type of leak unless your gasket has holes in it as well. A mechanic can easily replace some of these rings, and other rings require tearing down the engine to get to them.
Reason #2: Incorrectly Installed Gasket
The next issue could be a gasket pan or gasket cover that was not installed properly. If a valve cover gasket is tightened too much, the oil will not go where it should and can end up leaking out because the gasket is too tight. The oil pan gasket also needs to be properly attached. If the oil pan gasket is attached too loosely, oil can leak around this gasket, flowing out as your vehicle is in use. Over and under-tightening various gaskets can lead to oil leaking from your vehicle.
Reason #3: Damaged Pans & Gaskets
The oil pan for your vehicle and the gaskets that control the oil are all located on the underside of your vehicle. Although shields are often put in place to protect the underside of your vehicle from damage, road debris can still cause damage to these important components. Even things such as hitting potholes can contribute to damage to the pans and gaskets that are connected to your engine on the underside of your car. After many miles, it is not uncommon for the oil pan gasket to get damaged, resulting in leaking oil.
Bad valve seals, incorrectly installed gaskets, and damaged gaskets are all common issues which can cause oil to leak. If you have oil leaking out from under your vehicle, get it to the auto repair mechanic so they can address the underlying issue behind the leak.