If you notice your car leaking oil when parked, you have a problem that needs to be fixed. There are several possible reasons why your car is leaking oil… some of them are not-so-bad, and some of them are big problems that will be expensive to fix.
In this article, you’ll learn about the top ten reasons for your car leaking oil when parked.
Before we get into it, I want to give a Three Bay Garage PSA…
Check your oil ASAP if you notice your car leaking oil when parked!
This will be common sense to many people, but for the newbies and the (ahem) not-so-bright people out there, I need to say it.
Oil is your engine’s lifeblood. Its purpose is to keep the engine’s moving metal parts lubricated.
So if your engine is losing oil, you damn-well better keep a watchful eye on your oil level. You’ll need to regularly top it off until you fix the cause of the leak. If you don’t, your problems will be much worse than your car leaking oil when parked!
OK, now that we’ve gotten that out of the way, here’s the top ten reasons for your car leaking oil when parked. I list them in order of severity from “no big deal” to “oh shit!”
Top ten reasons why your car is leaking oil when parked
1. Missing or broken oil filler cap
Your oil filler cap is the cap on top of your car’s engine that covers the opening where you add oil. If you drive without this cap on, you’ll start losing oil through the opening.
But why would someone drive around without their oil cap? Well… mistakes happen and I know from firsthand experience. As an Audi driver, adding oil to my engine is a regular (and frustrating!) practice. My allroad consumes about a quart of oil every 1,000 miles. During one of my routine (grr) oil top-offs, I forgot to replace my filler cap. Because of this, oil shot up through the opening and created an oil leak.
Similar leaking activity can happen if your cap is broken or doesn’t seal properly. So if you have a broken oil cap, replace it. It’s a cheap an easy thing to fix.
2. Bad oil pan plug
Your oil pan plug is the bolt on the bottom of your oil pan that you remove to drain the oil out of your car’s engine. Removing this plug is one of the first steps in changing your car’s oil.
Depending on your car, some drain plugs use washers or rubber seals to help properly seat the plug into the oil pan.
You guessed it… things happen to these washers and seals. Maybe a rubber seal wears out with age. Maybe the washer was bent when someone over-tightened the plug. Or maybe it was forgotten to be put back on during your last oil change.
Whatever the cause, if you discover oil leaking from the area around your oil pan plug, it’s another easy fix. Buy the correct OEM-specific oil pan plug for your car and replace it.
Just remember, if you remove the oil pan plug, you’ll drain your car’s oil. So be ready for it!
3. Oil filter problems
If you notice oil leaking from your oil filter, ther are several possibilities as to why it could be the reason for you car leaking oil when parked.
Double gasket
There is generally a gasket on the oil fiter that matches up to your car’s oil filter housing. Sometimes the old gasket sticks to the housing. If this happens and you overlook it when changing your oil, you’ll have two gaskets in place. This can cause an oil leak.
Damaged gasket
If the gasket on your oil filter is damaged, it can cause a leak. These gaskets rarely wear out and typically last through the duration of an oil change, But, if you haven’t changed your oil in a long time (shame on you!) the gasket can wear out due to old age.
Over-tight or loose filter
If you over tighten your oil filter, you risk squooshing (is that a word?) the gasket. The overly-compressed gasket won’t set properly and will create an opportunity for a leak. On the flip site, if your filter is too loose, it can start to leak oil. Constant vibration from your engine AND the pressure of the oil flowing through the filter can continue to loosen it, creating an even larger opportunity for a leak.
Damaged oil filter
Oil filters are often located on the bottom of an engine. This location is prone to potential damage. Maybe you kicked up a rock or bottomed out on something. Whatever the cause, an impact to your oil filter can damage it and cause it to leak oil.
Wrong oil filter
Mistkes happen! Maybe you or the person performing your last oil change used the wrong-sized oil filter. A wrong-sized filter won’t seal properly and therefore will result in leaking oil.
No matter the cause of the problem with your oil filter, replacing it is an easy fix. Oil filters are cheap and easy to replace.
4. Bad oil pan gasket
A very common reason for your car leaking oil when parked is a bad oil pan gasket.
When your engine isn’t running, the oil stops flowing and it settles to the bottom of your engine in the oil pan. A gasket is necessary to prevent leakage from the area where the oil pan bolts to the engine.
And of course, as you probabably know… gaskets can and will wear out over time. To make matters worse for your oil pan gasket, it’s generally located at the very bottom of an engine and therefore constantly exposed to all the crap and chemicals on the road.
Depending on your car, replacing an oil pan gasket is generally an fairly easy job. Because it’s typically on the bottom of the engine, there’s not a lot of other parts in the way. Just drain the oil, unbolt the pan, replace the gasket, and re-attach.
5. Damaged oil pan
As you just read, your car’s oil pan is typically located at the bottom of your engine. Given the location, there is a chance it can get damaged and cause an oil leak.
This is a pretty rare reason for an oil leak. If you have oil leaking from a damaged oil pan, you’ll probably know the reason why. Oil pans are pretty sturdy parts. In order to damage them, you’re going to have to do something fairly extreme like running off the road and bottoming out on a curb.
Bottom line, it’s going to take a real hard impact to damage your oil pan. The good news is this: given its location on the bottom of the engine, it’s fairly easy to replace, and therefore not too expensive of a fix.
6. Bad valve cover gasket
A bad valve cover gasket is another common culprit of your car leaking oil when parked.
Valve covers are the rectangle-shaped covers that sit on top of your engine’s head. If you see oil leaking out from the area where the valve cover attaches to the head, chances are you have a bad valve cover gasket.
While not as easy to fix as the previously-mentioned reasons for an oil leak, it’s still not a terribly difficult job to perform. A valve cover gasket is an inexpensive part. The cost in this job has to do with the labor.
If you’re a comfortable and confident DIY’er, this is a job you can probably take on. For a sense on what it will take to do yourself, here’s a pretty good video from Car and Driver Magazine:
7. Timing chain cover gasket
If your car uses a timing chain (instead of a timing belt) it requires lubrication. So some of your engine’s oil circualates around your timing chain to keep it lubricated.
Because oil is flowing around in this area, a gasket is required. And just like all gaskets on your engine, it can eventually wear out.
So if you see oil leaking out from around your timing chain cover, it’s a sign that you need to replace your timing chain cover gasket.
This isn’t the easiest job to do. As with most gaskets, the part is inexpensive. This cost is high because of the labor involved in getting to the gasket. It’s not an easy area to access and I would say this is an advanced DIY job.
A word on timing chains vs timing belts
Keep in mind this only applies to cars that use timing chains. Timing chains and timing belts serve the same purpose. Timing belts do not require lubrication. For a great explanation about timing chains vs. timing belts, check out this article on the Napa Know How blog.
If your car has a timing belt, and you see oil leaking from around the timing belt cover, you may have a blown camshaft seal. This makes a great segue to the 8th reason why your car is leaking oil when parked…
8. Blown camshaft seal
First… here’s a quick “camshaft 101” lesson: Your camshafts control the intake and exhaust openings in your engine. In newer cars, they are typically located in your cylinder heads and constantly spin while your engine is running. They require lubrication from your engine’s oil. They are spun by either your timing chain or timing belt.
Where camshafts exit the cylinder heads and connect to the timing belt or chain, a round, rubber seal is used to contain the oil in the cylinder heads. These seals are very durable, but, like anything else, camshaft seals can wear out over time.
Oil leaking from blown camshaft seals can be tricky to spot. The most common area you’ll see it coming from is at the bottom of the timing belt cover. It is also often accompanied by your car burning oil. So you’ll also notice blueish smoke coming from your exhaust.
The good news is that this is a fairly uncommon cause for your car to leak oil when parked.
The bad news is that this is a difficult and expensive job. The cost of the seal is low, but the labor involved to get to it is high.
9. Front or rear crank seal
The crank shaft is basically the backbone of your engine. It converts the linear energy from combusion into the rotational motion that powers your car’s wheels.
Both ends of the crank shaft have seals on them. Both of these seals can wear out and cause your car to leak oil when parked. Luckily, seals are more durable than gaskets. So blowing either of thes seal isn’t as common as gasket failures.
Front Crank Seal
If you see oil dripping from this area, chances are your front main seal is bad.
The front crank seal is located at the front of your engine, behind the harmonic balancer (the large pulley that powers all belts in your engine).
Replacing this seal is not an easy job. Depending on your car, it can be very difficult to get to. Like most seals and gaskets, the part is inexpensive, but getting to it is difficult.
Rear crank seal
Also know as the rear main seal, your rear crank seal is at the rear of your engine where the crankshaft exits and enters the transmission.
If you see oil leaking out from the area where your engine and transmission meet, chances are you have a blown rear crank seal.
This is no easy job at all. It often requires removal of either your car’s engine or transmission. It is not an easy DIY project at all. And it will be quite costly to repair.
10. Blown head gasket
Ah, the blown head gasket. One of the most dreaded phrases most car owners never want to hear.
Cylinder heads are bolted directly on to your car’s engine block. And between them is sandwiched a head gasket.
Head gaskets can blow out due to old age or because your car overheated. If you see oil dripping out between your engine block and cylinder heads, it’s time to cry.
In order to get to the head gaskets, the entire top of the engine has to be removed. It is a very expensive and time-consuming job. In fact, depending on the age and condition of one’s car, many people often scrap their cars if they have a blown head gasket.
Car leaking oil after oil change
If your probelm is a car leaking oil after oil change, don’t get too concerned. Yet.
After an oil change, sometimes oil gets spilled and ends up in a spot in your engine compartment that you can’t clean. As your car moves, it can get jarred free and end up in a spot that causes your car to leak oil when parked.
With all the shielding under cars these days, it’s easy for a small spill to pool somewhere out of sight after an oil change.
So if you have a car leaking oil after oil change, keep a close eye on it. If it doesn’t clear up, go through the list above and try to pinpoint the trouble spot.
Conclusion
A car leaking oil when parked is concerning. Oil is your engine’s lifeblood. Losing it is not a good problem to have. If you do have an oil leak, be sure to constantly keep an eye on your car’s oil level and maintain a safe level. Then go through the steps to find the source of your oil leak and have it fixed.