You’re driving and suddenly, the oil light flickers on your dashboard, again. You check for puddles under your car, but there’s nothing. It’s not yet time for an oil change, so what’s happening? If you’re experiencing oil loss without any visible leaks, your engine might be burning oil. Let’s dive into why this occurs and what you can do about it.
Low Oil Levels But No Leak? Burning Oil Could Be the Culprit
When your car mysteriously starts losing oil, the issue usually boils down to two possibilities: an external leak or internal oil consumption, also known as burning oil. While external leaks are often easier to spot, internal burning can be more elusive. Even if you don’t see oil dripping onto your driveway, subtle issues within your engine can cause it to burn oil.
During a routine oil change service, a comprehensive inspection can often identify visible leaks. However, if you consistently need to add oil between scheduled changes and no external leaks are apparent, your vehicle is likely burning oil internally.
Is My Car Burning Oil? Key Signs to Watch For
Burning oil happens when engine oil seeps into the combustion chamber and gets burned along with fuel. A telltale sign is bluish smoke emanating from your exhaust pipe. However, this symptom might not always be obvious, especially if your engine is only burning small amounts of oil. Even without visible smoke, consistently low oil levels are a major red flag.
Ignoring excessive oil consumption can lead to significant engine damage and costly repairs down the line, particularly in older vehicles with higher mileage. While some oil consumption is considered normal, especially in older cars, newer vehicles should not require frequent oil top-offs between changes. If you’re adding more than a quart of oil between changes in a newer car, it’s time to investigate.
Common Causes of Engine Oil Burning
When engine oil finds its way into the combustion chamber, it’s usually due to wear and tear on internal engine components. Modern engines using low-viscosity oils, such as 5W-20, can be more susceptible to oil burning even with minor wear. Here are some of the most frequent culprits behind excessive oil consumption:
1. Faulty PCV Valve
The Positive Crankcase Ventilation (PCV) valve is a critical part of your engine’s emission control system. It’s designed to vent harmful gases from the crankcase back into the intake manifold to be burned in the combustion chamber.
Alt text: Diagram showing the location and function of a PCV valve in a car engine, highlighting its role in recirculating crankcase gases.
When the PCV valve fails or becomes clogged, crankcase pressure can build up. This increased pressure can force oil past seals and gaskets, leading to oil being sucked into the intake manifold and burned during combustion. Often, replacing a malfunctioning PCV valve is a straightforward and relatively inexpensive fix.
2. Worn Piston Rings or Damaged Cylinder Walls
Piston rings are essential components that create a seal between the pistons and cylinder walls. This seal is crucial for maintaining engine compression and preventing combustion gases from leaking out.
Alt text: Illustration depicting worn piston rings and damaged cylinder walls in an engine, causing oil to leak into the combustion chamber.
Over time, piston rings can wear down, or cylinder walls can become scored or damaged. When this happens, the seal weakens, allowing engine oil to seep into the combustion chamber. This results in oil burning and reduced oil levels. Repairs for worn piston rings or cylinder walls can be extensive and costly, often requiring significant engine work.
3. Deteriorated Valve Stem Seals
Valve stem seals are small rubber seals that sit on the valve stems, controlling the amount of oil that lubricates the valves as they move within the valve guides.
Alt text: Cross-section diagram of an engine valve stem seal, showing its position on the valve stem and its function in regulating oil flow for lubrication.
As valve stem seals age, they can become brittle, cracked, or worn. When valve seals fail, they lose their ability to regulate oil flow effectively, allowing excess oil to leak down the valve stems and into the combustion chamber. Replacing valve stem seals is less labor-intensive than piston ring replacement but still requires specialized tools and expertise.
Stop Burning Cash: Address Oil Burning Issues Promptly
Suspect your car might be burning oil? Don’t ignore the signs. Addressing the issue early can prevent more serious engine damage and save you from expensive repairs down the road.
A comprehensive oil change service is a great starting point. At Firestone Complete Auto Care, our full-service oil change includes a 19-point inspection to help identify potential issues, including oil leaks and signs of engine wear. We also offer advanced oil leak detection services using dye to pinpoint even subtle leaks.
Don’t let burning oil burn a hole in your wallet. Visit your nearest Firestone Complete Auto Care or schedule an appointment online today for expert oil care and vehicle maintenance.
