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3 months ago

Car Oil Leaking – Diagnosis, Causes, and DIY Fix

Car Oil Leaking – Diagnosis, Causes, and DIY Fix

Engine oil is the single most important thing to keep your car running. It lubricates the internals of the engine and prevents them from heating up and wearing out. If the engine oil level in your car is below the specified limit, it can result in catastrophic engine damage resulting in the car being rendered, unable to run, and the subsequent repairs can amount to thousands of dollars. 

Just like any other fluid, engine oil can leak from the car, and if left unchecked, results can be disastrous. In this post, we will look at the main causes of oil leaks, how to diagnose your car and how you can fix it at home.

What are the Causes of Oil Leak in a Car?

The oil inside your car is under tremendous pressure when the engine is running. To make sure that it does not leak, gaskets are used at any point where two parts of the engine are joined together. With that in mind, here’s a list of possible causes: 

  • Leaking valve cover gasket
  • Leaking oil pan gasket
  • Punctured or damaged oil pan 
  • Leaking oil filter o-ring gasket
  • Incorrectly installed seals or gaskets

Before you get your car repaired, it is important to make sure that what’s leaking is actually engine oil and where it is leaking from.

Diagnosing Oil Leaks 

Make a habit of checking oil levels in your car at least once a week. The signs of oil leak in a car include but are not limited to: 

Oil Stains Under the Car

The most common sign of a car leaking oil when parked is the stains on the garage or driveway floor. If you see fresh oil or stains under the engine of the car, you have an oil leak. However, it cannot be said with certainty if the leaking fluid is engine oil or something else. 

Oil Level Warning Light 

Almost all cars have an oil level warning light in the instrument cluster. This is NOT the Check Engine light. Look for a red light in the shape of an engine with leaking oil or the word OIL that glows red when the engine is running.

Car Overheating 

Another sign of leaking engine oil is the engine heating up more than it should. While the engine oil lubricates and cools down the engine, make sure the levels don’t drop below the minimum limit which will cause the car to heat up. However, this can also be caused by a leaking radiator, so you need to look for other signs to make sure that the car is indeed heating up due to a lack of engine oil. 

Oil Burning Smell and Dense White Smoke

The engine of your car runs at high temperatures. If the oil leaks on the engine, it will burn. This leads to the characteristic oil burning smell and dense white smoke in the engine bay.  

Greasy Engine Bay 

If the inside of the engine bay of your car gets greasy a couple of days after cleaning it, you might have a little oil leak. 

Making Sure the Leaking Fluid is Engine Oil 

Engine oil is not the only fluid in a car that can leak. Cars also have other fluids such as brake oil, power steering fluids and more. So, before you start with engine oil leak repair, it is important to make sure that the leaking oil is actually engine oil.  

  • If there are drops of the leaking fluid, rub a little bit of them between your fingers to check the viscosity. Engine oil is viscous compared to most other engine fluids.
  • Check the level of all fluids in the car and monitor them for several days. The one with a dropping level is the one that’s leaking.

Pinpointing the Location of the Leak 

This is the trickiest part of the whole car leak fixing process. The engines of modern automobiles are complex pieces of machinery and are often crammed into tight spaces. That makes finding the exact location of the oil leak very difficult. 

If you have a car leaking oil after an oil change or you suspect the car has randomly started leaking oil, the first thing that you need to do is to clean the engine bay of the car thoroughly. Once you have done that, you can better pinpoint the location of the leak. 

Here are some tips on pinpointing the location of an oil leak: 

  • Start the engine and rev it up to increase engine temperature.
  • Ask someone to maintain the engine speed above 3,000 rpm and inspect the engine bay for oil oozing out or smoke coming from any location where any two parts of the engine are joined.  
  • If there is no visible leak in the engine bay, move under the car and look for droplets of oil on the oil pan or oil filter. 

After doing the above steps, one of the following locations will show where the oil is leaking: 

  • Oil leakage under the car from a damaged oil pan
  • Leakage from the oil pan gasket
  • Leakage from oil filter O-ring
  • Oil leaking from the front of the car from the valve cover gasket
  • Leakage from timing chain housing

All of these issues can be fixed except for oil leakage from the timing chain or timing belt housing. The slightest error can damage the timing chain or belt and the results can be expensive.

How to Fix an Oil Leak in Car 

The fix for the oil leak will depend on the location of the leak, as listed below. 

Oil Pan Leak Repair  

The oil pan is the reserve where the oil is stored. It is at the very bottom of the engine and can be damaged very easily. If you have a damaged oil pan: 

  • Buy a new one for your car’s make and model
  • Raise the car on jack stands
  • Drain the oil from the car
  • Unscrew the oil pan
  • Install a new oil pan, not forgetting the oil pan gasket

If the oil pan is not damaged and the leak is caused due to a faulty gasket, you can follow the above steps, just use the old pan and replace the gasket. You need to fully remove the old gasket from the oil pan and the engine. If pieces of the old gasket are left on the mating surfaces, the new one won’t seat properly, leading to leaks in the future. 

Oil Filter Leak Repair 

If the leak is originating from the oil filter, the cause is a failed o-ring that secures the filter to the engine. 

  • Drain the oil from the engine
  • Unscrew the oil filter
  • Replace the o-ring and install the filter back on the car

Valve Cover Leak Repair 

If the oil leak is not under the engine but inside the engine compartment from the valve cover. 

  • Open the valve cover
  • Remove the vacuum lines from the cover
  • Carefully remove the oil cover gasket from the valve cover and the cylinder head
  • Install the new gasket and apply RTV on any points not covered by the gasket
  • Tighten the valve cover back in place

Exercise Caution 

When working with engine oil, you need to take care of the following things: 

  • Do not work on a hot engine. Let it cool for at least an hour before you start working. 
  • Used engine oil is carcinogenic and can cause skin problems. Use gloves when working. 
  • If the engine oil has completed the mileage, do not reuse it. Replace it with a new one.
  • If you are changing the engine oil, ALWAYS change the oil filter with it.

Disclaimer: If you have limited knowledge of cars, consult a mechanic instead of trying to rectify the problem on your own.

Frequently Asked Questions

Why is my car leaking oil?

The main reasons behind leaking oil are faulty gaskets in the oil pan, oil filter, valve cover or timing chain cover. 

What causes the oil pan gasket to leak?

The main reason for a leaking oil pan gasket is an incorrectly installed oil pan or the gasket having completed its life. 

How much does it cost to repair an oil leak?

Car oil leak repair cost depends on the nature and amount of the leakage. If the leak is due to a simple problem, you can fix it for under $100 at home. In case of more serious problems, like a head gasket leak, you might need to spend upwards of $1,000 to fix the leak.

Can I drive a car with an oil leak? 

If the leak is small and the oil level is not under the minimum limit, you can drive the car but do not rev it high and get the problem fixed as soon as possible. 

Do I need an oil change if the car is leaking oil?

Do not change the oil if there is a leak. If you get the repair done when the oil has completed its life, replace it. If the oil is fresh, you can reuse it but do not mix it with burnt-out used oil.