As vehicles age and rack up the miles, oil leaks become a more common issue. Engines in high-mileage vehicles have gone through years of heat cycles, pressure, and wear. Even the best-maintained cars eventually develop small problems that can lead to oil escaping from where it shouldn’t.
If you drive a vehicle with over 100,000 miles, keeping an eye out for signs of oil leaks is key to preventing major engine damage. Below are five of the most common reasons high-mileage engines start leaking oil.
1. Worn Valve Cover Gasket
The valve cover sits at the top of your engine and is sealed by a gasket that keeps oil from leaking out. Over time, this gasket can become brittle or cracked from exposure to heat and age. Once it begins to fail, you may notice oil seeping down the sides of the engine or a burning oil smell if it leaks onto hot parts like the exhaust manifold.
While this is often a minor repair, it’s important to fix it early. Ignoring a leaky valve cover gasket can eventually affect ignition components and lead to more expensive repairs.
2. Degraded Oil Pan Gasket
Located at the bottom of the engine, the oil pan holds the majority of your vehicle’s motor oil. A gasket seals the pan to the engine block, but in older vehicles, this gasket can start to leak. You might notice oil spots under your car or a gradual drop in oil levels without any dashboard warning lights.
On some cars, replacing the oil pan gasket can be straightforward. On others, it may require removing other parts to access the gasket. Either way, addressing the issue prevents oil from dripping out during daily use.
3. Hardened or Shrinking Engine Seals
High-mileage engines rely on several rubber or silicone seals to keep oil in its proper place. Over time, these seals can shrink, dry out, or harden, losing their ability to do their job. Front and rear main seals are common culprits. When these seals fail, you may not notice a leak right away, but your engine oil will slowly disappear over time.
If you’re constantly topping off oil without any visible puddles, a technician can help inspect the seals and identify hidden leaks. Replacing seals can be more involved than gasket work, but it's often necessary to keep an engine healthy.
4. Improper Oil Filter Installation
Believe it or not, something as simple as an oil filter can cause a leak. If the filter was installed too loosely, tightened too much, or if the gasket from an old filter wasn’t removed during an oil change, oil can escape from that point. This kind of leak may be obvious shortly after a recent oil change.
Always be sure your oil filter is installed properly by a trained technician using the correct part for your vehicle. A small mistake here can lead to rapid oil loss.
5. Cracks in the Engine Block or Oil Pan
In rare but serious cases, high-mileage engines may develop hairline cracks in the oil pan or even in the engine block itself. These cracks can be caused by repeated heat stress, poor maintenance, or damage from road debris. If you notice major oil loss, a strong smell of burning oil, or signs of overheating, a deeper inspection may be needed.
Cracks often require replacement of the damaged component and shouldn't be ignored. They can worsen quickly and result in complete oil loss or engine failure.
How to Spot an Oil Leak Early
- Watch for oil stains or drips where your car is parked.
- Check your oil level regularly with the dipstick.
- Pay attention to burning smells or smoke from under the hood.
- Look for signs of oil residue around the engine bay.
- Monitor engine performance and fuel efficiency.
Why Timely Repairs Matter
Even small oil leaks can create big problems over time. If your engine runs low on oil, it will lose its ability to stay cool and properly lubricated. This can lead to increased friction, heat damage, or even engine seizure in severe cases. Catching leaks early is the best way to protect your high-mileage vehicle and extend its lifespan.
Let Friendly Auto Centers Help Keep Your Engine Leak-Free in Mesa, AZ
At
Friendly Auto Centers in Mesa, AZ, our team specializes in diagnosing and repairing oil leaks in vehicles of all ages. Whether it’s a worn gasket, hardened seal, or another issue, we’ll find the source of the leak and fix it the right way. Don’t wait until it turns into a major engine problem. Schedule your inspection today and keep your high-mileage vehicle running strong.
