How to Locate an Oil Leak in Your Car

How to Locate an Oil Leak in Your Car

Though a car has a variety of fluids that can potentially leak out (see What's That Puddle Under the Car?), oil—thick black or brown liquid—is the most common to do so. Depending on the source of the leak, dripping oil can be a quick fix or a major repair. Determining the source can help you gauge the seriousness of the problem. After exhausting the steps in this tutorial, take a car that's leaking oil to the mechanic and cross your fingers.


• Work gloves

• Rags

• Filter wrench or ratchet

• Wheel chocks


• Engine cleaning solvent

• Talcum powder

1 Block the tires securely with wheel chocks. Put the car in park with the emergency brake on, and start the vehicle. Look underneath the car for the source of the leak, but please keep yourself safe—refrain from putting your body under a running vehicle. It's likely that an oil leak from under the car will require attention from a mechanic.

How to Locate an Oil Leak in Your Car

2 Check the oil plug and filter. Because these are the spots you fidget with when changing the oil, they are also the most frequent source of a leak. If you spot a leak in one of these two places, first check that the plug or filter is attached snugly. (See How to Change the Oil in a Car, for safety precautions before diving under the car.) If that doesn't fix the leak, remove the plug and filter to check the integrity of the rubber gaskets. If needed, the gaskets are easy to replace. Note that removing either will release oil, so change into work clothes and have rags handy. (While you're at it, change the oil, if it's due!)

How to Locate an Oil Leak in Your Car

3 Check the valve covers. Many cars with over 30,000 miles on them will develop subtle leaks from the valve cover sealing the top of the engine. Because these leaks tend to attract and trap dirt and grime, they should be obvious once you raise the hood and look around. If you find the leak here, breathe a sigh of relief—valve covers are inexpensive and easy for a pro to replace.

4 Check the pump. This is a common oil leak location. It's also a leak you want to catch early, as a leaking pump can be diagnostic of a bigger problem, and if the oil pump fails, it will fail to lubricate the bearings in your engine and the system can overheat and seize. Check the seals on either side of the pump to see if they are leaking oil. If you see a leak, oil pump seals are easy to replace. If the pump is leaking, but it's not the seals, you might need a whole new pump.

How to Locate an Oil Leak in Your Car

5 Degrease the engine with aerosol cleaning solvent. If the location of a leak isn't immediately obvious, you'll likely need to do some cleaning to spot the problem—if everything's covered in oil, it's impossible to tell where a little extra is coming from. Wearing gloves, use a rag to clean around the valve covers, the engine block, and under the oil pan. If needed, you can get the engine professionally steam-cleaned, after which a leak location should be obvious. If oil appears to be seeping from solid metal, look for tiny cracks, which can be made visible by sprinkling the suspected leak location with talcum powder. Though you may be able to stop very small leaks temporarily with spray-on fluids that are like heavy paints (ask the folks at your local auto-supply store which brands to use), metal with hairline cracks can't spontaneously heal itself. You'll need to replace the parts.

What's That Puddle Under the Car?

As the human body ages, it's increasingly prone to mysterious pains and pops and odd tweaks—if you can just ignore the discomfort for a couple of days, it generally goes away. The same is not true of your car. Unless you have a minor issue like a pebble in your tire making a clicking noise, your car's minor ailments will likely only get more severe. That's especially true of leaks. A leak won't spontaneously plug itself—you've got to do the plugging yourself. First, though, you have to figure out what's leaking. Fortunately, the fluids inside your car come in a rainbow of hues, making for fairly simple diagnostics. Park your car on top of an old, white sheet and then leave it for a couple of hours or overnight. Then match the color to the list below—and get thee to a mechanic, or an auto-parts shop, right away.

Red. Though some newfangled, long-life coolant is red, the rosy fluid leaking from your car is more likely power steering or automatic transmission fluid. It's time to see a mechanic.

Clear. A clear fluid might just be water from the condenser on the air conditioner unit, which is not a bad thing. If you've been using the AC recently and the clear fluid seems to come from near the AC, you may not need to do anything about it at all—a little condensation from the AC is perfectly normal. But it might also be power steering fluid, which is bad. Smell to determine which. If it's not water, get to a mechanic.

Amber. Do you smell gasoline? If so, the amber fluid is almost certainly a gas leak and it's time to visit a mechanic. If not, consider the amber liquid yellow or brown. See here for the possible identity of the fluid.

Green. Bright green, slippery fluid is coolant, likely dripping from the radiator or engine. Unfortunately, antifreeze tastes good and is toxic to pets, and so the puddle of coolant under your car may be doing harm to more than just your car. Check all the connecting hoses as well as the integrity of the reservoir. If you find an obviously faulty hose or reservoir, you can consider replacing it yourself. If the source of the leak remains elusive, head to the mechanic.

Blue. Fluid that's blue is likely leaking from the windshield washing system, either from the reservoir itself or from a punctured or loose hose. Though blue is the most popular washing fluid color, it may also be pink or yellow. Again, if you can find the leaky part, you can evaluate replacing it yourself. If you can't find the leak, take it to a pro.

Yellow. Brake fluid starts out yellow and turns brown with time, so your mysterious fluid may actually be somewhere on the yellow/brown spectrum (although keep in mind that solid brown may be an oil leak). For obvious reasons, this is not a fluid leak you should take lightly. If you can test your brakes with no consequences or danger in your driveway, do so, and then drive to the nearest mechanic. If you are at all nervous, have the car towed.