Engine Oil Leak: Causes, Signs, and What to Do
Notice oil spots under your car? Learn the common causes of engine oil leaks, how to identify the source, and when you need professional repair.
Is Your Car Leaking Oil?
Finding oil spots under your car is always concerning. While some oil seepage is normal in older vehicles, significant leaks can lead to engine damage, fire hazards, and environmental problems. Here's how to identify and address oil leaks.
Signs of an Oil Leak
- Oil spots under your car (dark brown or black liquid)
- Burning oil smell while driving
- Blue smoke from the exhaust
- Oil level dropping between changes
- Low oil pressure warning light
- Visible oil on engine components
Common Causes of Oil Leaks
1. Degraded Engine Gaskets
Gaskets seal the connections between engine components. Over time, they harden and crack from heat exposure.
Common culprits:
- Valve cover gasket
- Oil pan gasket
- Timing cover gasket
Repair cost: $100-$500+ depending on location
2. Oil Pan Damage
The oil pan sits at the bottom of your engine and can be damaged by:
- Road debris
- Speed bumps and potholes
- Improper jacking
Repair cost: $150-$500
3. Oil Drain Plug Issues
The drain plug is removed during oil changes. Problems include:
- Loose plug
- Damaged threads
- Worn washer
Solution: Tighten plug, replace washer, or repair threads
4. Oil Filter Problems
A loose or faulty oil filter can leak significantly.
Causes:
- Not tightened properly during oil change
- Damaged gasket
- Wrong filter for your vehicle
Solution: Replace filter and gasket ($10-$30)
5. Valve Cover Leaks
The valve cover sits on top of your engine. Its gasket commonly leaks on older vehicles.
Signs: Oil visible on the top/sides of the engine
Repair cost: $150-$350
6. Front or Rear Main Seal
These seals where the crankshaft exits the engine are more serious repairs.
Signs: Oil at the front or back of the engine/transmission junction
Repair cost: $400-$1,000+
7. Oil Cooler Lines
Vehicles with oil coolers have lines that can leak at fittings or develop cracks.
Repair cost: $150-$400
How to Locate an Oil Leak
1. Check the Oil Level
First, verify oil is actually low. A full oil level with spots might indicate something else leaking.
2. Look for the Source
Clean the engine area and watch where fresh oil appears. The highest point of oil is usually closest to the source.
3. Use UV Dye
Mechanics can add UV dye to your oil, then use a special light to trace the leak path exactly.
4. Perform a Pressure Test
For hard-to-find leaks, mechanics can pressure-test the system to find the leak source.
Is It Safe to Drive With an Oil Leak?
Small seep/minor leak: Usually safe for short term if you monitor oil level and top off as needed.
Significant leak: Risky. Low oil can cause:
- Engine overheating
- Increased engine wear
- Complete engine failure
Active drip onto hot components: Fire hazard. Get it fixed immediately.
Prevention Tips
- Change oil on schedule
- Use quality oil and filters
- Check oil level monthly
- Address small leaks before they become big ones
- Have cooling system maintained (overheating damages gaskets)
Mobile Oil Leak Diagnosis in NYC
Not sure where your leak is coming from? NYC Mobile Auto Assist can diagnose oil leaks at your location and perform many repairs on-site. We'll identify the source, explain your options, and help you decide the best course of action.
Don't ignore that oil spot—call us for a diagnosis.
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