Why Is My Car Leaking Oil After an Oil Change?

Loose or Misaligned Oil Filter

One of the most common reasons drivers wonder, “Why would my car be leaking oil?” after a service is a simple one: the oil filter isn’t seated quite right. Filters need to be tightened to a very specific level—neither too loose nor too tight. If the old gasket sticks to the engine block or the new filter isn’t aligned perfectly, oil can seep out once the engine warms up and pressure builds.

It’s a small issue, but it can create a surprisingly noticeable leak.

Drain Plug Issues

The drain plug is the bolt at the bottom of your oil pan that gets removed during every oil change. If it’s cross‑threaded, under‑tightened, over‑tightened, or fitted with a worn‑out washer, oil can escape around it. Sometimes the plug itself is fine, but the washer (also called a crush gasket) has flattened out over time and no longer seals properly.

A tiny gap is all it takes for oil to drip.

Wrong Type or Amount of Oil

Using the wrong viscosity can cause oil to move through the engine differently than intended. Too thin, and it may slip past seals more easily. Too thick, and it may create pressure that pushes oil out of weak points. Overfilling the engine can also cause leaks because excess oil gets whipped into foam by the crankshaft, increasing pressure and forcing oil out of seals.

This is one reason it’s important to know “Why is my oil leaking?” instead of ignoring the signs.

Old or Worn Seals Revealed by Fresh Oil

Sometimes the oil change isn’t the cause of the leak—it just makes an existing issue more noticeable. Fresh oil is thinner and flows more easily than old, dirty oil. If your engine has aging gaskets or seals, the new oil may slip through spots where thicker, older oil didn’t.

This is especially common in higher‑mileage vehicles or engines that have gone too long between oil changes.

Residual Oil From the Service

Not every oil drip means something is wrong. Occasionally, a small amount of oil spills onto the engine or frame during the service. When the engine heats up, that leftover oil can drip down and make it look like there’s a leak. This usually clears up within a day or two.

If the spot keeps growing, though, it’s time to get it checked.

Why You Shouldn’t Ignore an Oil Leak

Even a small leak can turn into a big problem. Oil is your engine’s lifeblood—it lubricates moving parts, reduces friction, and keeps temperatures under control. When oil levels drop, parts wear faster, heat builds up, and the risk of engine damage increases.

A leak after an oil change might be something simple, but it’s never something to shrug off. Catching it early can save you from costly repairs down the road.

When to Bring Your Vehicle Back In

If you notice oil spots under your car, smell burning oil, or see smoke from under the hood, it’s time to have the vehicle inspected. Nissan Lake Country’s service team can pinpoint the source quickly and let you know whether it’s a minor fix or requires more attention.

Most of the time, post‑oil‑change leaks are easy to resolve. The key is to get ahead of them before they become something bigger.

Don’t Wait—Get It Checked

Oil leaks aren’t something to panic about, but they’re definitely something to take seriously. Whether it’s a loose filter, a worn seal, or a drain plug issue, the sooner it’s diagnosed, the better your engine will be in the long run. If you’re noticing your car leaking oil after an oil change, swing by Nissan Lake Country in Oconomowoc. A quick inspection can give you peace of mind and keep your vehicle running the way it should.