How long should your engine oil last?

For most modern cars running full-synthetic oil and a quality filter, expect 7,500–10,000 miles (12,000–16,000 km) or about 12 months between changes under normal driving, while older engines or severe use may need 3,000–5,000 miles (5,000–8,000 km) or 6 months; always follow your owner’s manual or the vehicle’s oil-life monitor. Engine oil life depends on the oil type, the engine’s design, software that tracks oil degradation, and how and where you drive. Here’s how to gauge the right interval for your vehicle—and when to change sooner.

What “oil life” really means

Oil life isn’t about how much oil is left in the pan; it’s about how well the oil still protects your engine. Over time, heat, oxygen, and contaminants break down the base oil and deplete additive packages that control acidity, prevent corrosion, and keep particles suspended. Viscosity can shear thinner at high rpm, or thicken from oxidation and soot. Modern engines—especially turbocharged and gasoline direct injection (GDI) units—can fuel-dilute the oil, weakening its film strength. When oil can no longer maintain viscosity, neutralize acids, or keep the engine clean, it’s time to change it.

Typical intervals by oil type and vehicle

Intervals vary widely with oil formulation, engine design, and manufacturer guidance. Use the list below as a practical range, then cross-check with your owner’s manual and the in-car oil-life monitor.

• Full-synthetic (gasoline engines, normal use): 7,500–10,000 miles (12,000–16,000 km) or up to 12 months; some extended-performance oils and OEMs permit up to 12,000–15,000 miles (19,000–24,000 km) when explicitly approved.
• Synthetic blend: 5,000–7,500 miles (8,000–12,000 km), typically 6–12 months.
• Conventional/mineral: 3,000–5,000 miles (5,000–8,000 km), typically 3–6 months, though many modern engines specify synthetic only.
• European flexible-service systems (with approved long-life oils): up to 10,000–20,000 miles (16,000–32,000 km) or 12–24 months, depending on OEM specs (e.g., BMW LL, Mercedes MB, VW/Audi 504/507). Use only the exact spec oil.
• Light-duty diesel pickups/SUVs: 5,000–10,000 miles (8,000–16,000 km) or 6–12 months; regen cycles and towing may shorten this. Low-SAPS oil is often required for DPF longevity.
• Turbocharged/high-performance use: typically shorter than normal—often 5,000–7,500 miles (8,000–12,000 km)—due to higher temperatures and shear.
• Hybrids with frequent short trips: time, not miles, often becomes the limiter; many owners change annually even at low mileage.
• Infrequently driven or classic cars: change at least annually regardless of miles to remove moisture and acids; use the correct viscosity and spec for older seals and metallurgy.
• Track, towing, extreme heat/cold, or dusty conditions: shorten intervals; some owners change after events or halved intervals.
• Electric vehicles: no engine oil required, though they still need other fluid services (e.g., gear oil, coolant) per schedule.

These ranges are starting points. Manufacturer specifications and your vehicle’s oil-life monitor should take precedence, especially when a warranty is involved.

Factors that shorten oil life

Certain operating conditions accelerate oil degradation. If several apply to you, consider moving to the shorter end of the interval range or following the “severe service” schedule in your manual.

• Frequent short trips where the engine doesn’t fully warm up (condensation and fuel dilution).
• Extended idling and stop‑and‑go traffic (police, delivery, rideshare)—engine hours matter.
• Towing, heavy loads, mountain driving, or high ambient heat (thermal stress).
• Very cold starts (thick oil on startup, condensation) or frequent high‑rpm operation.
• Dusty or off‑road conditions (ingested particulates overload the filter and oil).
• Turbocharged/GDI engines (higher temps and potential fuel dilution).
• Poor maintenance history, sludge, or previous overheating.
• Contamination from coolant or fuel system issues (milky oil, strong fuel odor).

If your usage fits multiple severe conditions, adhere to the severe-service interval and consider periodic oil analysis to verify oil health.

What your oil‑life monitor is telling you

Most Oil Life Monitor (OLM) systems don’t directly “measure” oil quality; they use algorithms based on temperature, rpm, load, drive cycles, and time to estimate remaining oil life. Many vehicles prompt service at 15% and urge immediate changes at 5% or 0%. Always reset the OLM only after an oil and filter change, and don’t rely on the OLM to override a maximum time limit—many OEMs cap intervals at 12 months regardless of percentage. If your vehicle tracks engine hours, note that some manufacturers equate 1 engine hour to roughly 25–33 miles (40–53 km) for maintenance planning.

Time vs. miles: why calendar time matters

Even if you drive very little, oil absorbs moisture and fuel and its additives deplete. That’s why many carmakers specify an annual oil change maximum, even at low mileage. Some European flexible-service vehicles allow up to 24 months, but only with specific long-life oils and when the OLM permits it. If you mostly take short trips, the one-year rule is a smart upper limit.

Oil filters matter as much as oil

Your oil can’t outlast your filter. Long-life synthetic oils require filters rated for extended intervals; otherwise, the filter can go into bypass, circulating unfiltered oil. Replace the filter at every oil change, and match its service rating to your intended interval (e.g., filters marketed for up to 10,000–20,000 miles should only be paired with OEM-approved oils and intervals).

How to tell it’s time—beyond mileage

While the odometer and OLM are primary guides, other signs can indicate your oil needs attention sooner. Use the checklist below to spot issues early.

1. Dashboard alerts: OLM at low percentage, “Service engine oil,” or oil pressure warnings.
2. Fuel smell on the dipstick or rapidly rising oil level (possible fuel dilution).
3. Milky or frothy oil (possible coolant ingress—stop driving and diagnose).
4. Unusual engine noise on startup or under load (thin or depleted oil film).
5. Very dark, gritty oil with particles on the dipstick (heavy contamination—note that color alone isn’t a reliable indicator).
6. Heavy towing, track days, or extreme heat since the last change (shorten interval proactively).
7. Oil analysis results showing high wear metals, low viscosity, or low Total Base Number (TBN).

If you see any of these, change the oil and filter and address the root cause. Remember: oil color by itself is not a failure sign—lab testing is the definitive way to extend drains safely.

Specs and warranties: use the right oil

Use the viscosity and specification your manual calls for—such as API SP, ILSAC GF‑6A/GF‑6B for many modern gasoline engines, or ACEA and OEM long-life specs for European vehicles (e.g., BMW LL‑17 FE+, MB 229.5/229.52, VW/Audi 504 00/507 00). The wrong oil can trigger low-speed pre-ignition (LSPI), accelerate timing-chain wear, or damage aftertreatment systems. Keep receipts and service records to protect your warranty.

Quick reference: setting a sensible interval

If you need a fast rule of thumb while you verify your manual and OLM guidance, consider these baseline choices.

• Mostly highway, modern gasoline engine, full synthetic: 7,500–10,000 miles or 12 months.
• Mixed driving or some severe conditions: 5,000–7,500 miles or 6–12 months.
• Frequent short trips, towing, extreme temps, or lots of idling: 3,000–5,000 miles or 3–6 months.
• European long-interval systems with approved long-life oil: follow OLM; typically 10,000–20,000 miles with a 12–24 month cap.

Adjust from these ranges based on your vehicle’s requirements, your driving profile, and any alerts from the oil-life monitor.

Environmental note

Always recycle used oil and filters at an authorized collection point. One oil change’s waste can be re-refined into base oil, reducing environmental impact and conserving resources.

Summary

Expect 7,500–10,000 miles or about a year between changes with full-synthetic oil under normal driving, and 3,000–5,000 miles or six months for older engines or severe use. Let your owner’s manual and oil-life monitor set the ceiling, but shorten intervals for short trips, towing, turbo heat, extreme climates, or heavy idling. Use the exact oil spec your manufacturer requires, replace the filter every time, and consider annual changes even at low mileage.

Can a car lose oil without a leak?

Yes, a car can lose oil without a visible external leak, most commonly by burning oil internally. This occurs when oil slips past worn piston rings or failing valve stem seals into the engine’s combustion chamber, where it is then burned off with the fuel. Other internal causes for oil loss include a malfunctioning Positive Crankcase Ventilation (PCV) system, engine overheating, or using the wrong type or weight of oil, especially in an older engine. 
Internal Oil Consumption

• Worn Piston Rings: Opens in new tabIf the rings don’t create a good seal against the cylinder walls, oil can enter the combustion chamber and be burned. 
• Faulty Valve Stem Seals: Opens in new tabThese seals prevent oil from dripping onto the valves and into the combustion chamber. If they fail, oil can seep past and be burned. 
• PCV System Malfunction: Opens in new tabA clogged or stuck PCV valve can cause excess pressure and oil vapors to be drawn into the intake manifold, leading to oil consumption. 

Other Contributing Factors

• Engine Overheating: Opens in new tabA failing cooling system can cause the engine to overheat, leading to oil breaking down and evaporating more quickly. 
• Incorrect Oil Type: Opens in new tabUsing an oil that is too thin or not recommended by the manufacturer can cause higher oil consumption, especially in hotter conditions. 
• Normal Oil Usage: Opens in new tabEven in a healthy engine, a small amount of oil can be burned during operation; however, significant drops in the oil level between changes typically indicate a problem. 

What to do
If you notice your oil level is low but there are no puddles, it’s important to check for signs of internal oil consumption, such as blue-tinted exhaust smoke, especially when the engine is cold or accelerating. A mechanic can inspect the engine to diagnose the issue and recommend the appropriate repairs, which may involve replacing worn parts or addressing cooling system problems.

Does oil go bad in a sitting car?

Yes, engine oil goes bad sitting in a car, as it degrades over time due to oxidation, temperature changes, and moisture buildup from condensation. This contamination and chemical breakdown deplete the oil’s lubricating additives, reduce its effectiveness, and can lead to corrosion and sludge formation in the engine. Many experts recommend changing the oil every six to twelve months, even in low-mileage or unused vehicles, to prevent these issues. 
Why oil degrades over time:

• Oxidation: Even when a car is stationary, the oil is exposed to air and temperature fluctuations, which cause chemical changes and degradation. 
• Moisture and Contaminant Buildup: Condensation can form inside the engine and contaminate the oil, leading to acidity and corrosion of engine parts. Dust and other particles can also enter the oil over time, reducing its quality. 
• Additive Depletion: The chemical additives in oil, such as antioxidants and corrosion inhibitors, degrade and become less effective over time. 

Consequences of old oil:

• Reduced Lubrication: Opens in new tabDegraded oil is less effective at lubricating moving engine parts, which can lead to increased friction and wear. 
• Corrosion and Sludge: Opens in new tabMoisture and acidic byproducts from the degraded oil can cause rust and contribute to sludge formation. 

How to mitigate these risks:

• Follow the Manufacturer’s Schedule: Adhere to your vehicle manufacturer’s recommendations for oil change intervals, which are typically six to twelve months for cars that aren’t driven often. 
• Use the Right Oil: Synthetic oils generally last longer than conventional oils, but both can degrade once inside an engine. 
• Don’t Just Start the Car: Starting the car and letting it run for a short time is not sufficient; you need to get the engine up to full operating temperature to burn off moisture and contaminants effectively. 

How long should engine oil last in your car?

Engine oil doesn’t last forever and degrades with time and use, so it needs to be changed based on both mileage and time intervals, typically every 5,000-7,500 miles or at least once a year, though newer oils can last longer. Factors like short trips, harsh driving, and humidity can accelerate degradation. 
Mileage-Based Changes

• Conventional Oil: Requires more frequent changes, often around every 5,000 miles. 
• Synthetic Oil: Lasts longer, with intervals ranging from 7,500 to 20,000 miles, or 10,000-15,000 miles on average. 

Time-Based Changes

• Annual Change: A common recommendation is to change the oil at least once a year, even if the mileage limit isn’t reached. 
• Time Factor: Oil can degrade over time by absorbing moisture from the air, which can lead to the formation of acids and sludge. 

Factors Affecting Oil Life

• Driving Conditions: Opens in new tabShort trips and stop-and-go driving can prevent the engine from reaching optimal operating temperature, trapping moisture and fuel byproducts in the oil. 
• Engine Mileage: Opens in new tabHigh-mileage vehicles may benefit from specific additives found in “high mileage” synthetic oils. 
• Vehicle Age: Opens in new tabOver time, oil can degrade, and it’s a good practice to use fresh oil, especially in older cars. 

How to Check Oil Degradation

• Examine the Container: Look for a past expiration date (typically five years), separation, or sludge at the bottom of the oil container. 
• Check the Oil’s Color and Consistency: Hazy, murky, or separated oil indicates degradation. 
• Use an Oil Analysis: For a precise assessment, you can send an oil sample to a lab for a scientific analysis to determine the optimal oil change interval for your vehicle. 

What to Do If You Don’t Drive Often 

• Drive Periodically: Try to take the car out for a drive at least once a week or every other week, getting it up to temperature and driving for a bit.
• Aim for a Full Warm-Up: A proper drive helps evaporate any moisture in the oil that accumulates when the car sits idle.

Is oil life 50% ok?

No, 50% oil life is not “good”—it means your car’s computer has determined that the oil is halfway through its recommended lifespan and needs to be changed soon to continue properly lubricating and protecting the engine. While it’s not an emergency, delaying the oil change past this point can lead to increased engine wear and potential damage as the oil’s effectiveness diminishes significantly.
 
Why a 50% oil life warning is a call to action:

• It’s a real indicator: Modern oil life monitors (like a Ford IOLM) use algorithms to factor in driving conditions, temperature, and mileage to determine when the oil is no longer performing optimally. 
• It’s about more than just mileage: Even if you’ve driven fewer miles than the manufacturer’s standard, the oil can still degrade due to heat, moisture, and other contaminants. 
• Neglect leads to damage: The oil’s primary function is to lubricate engine parts and prevent friction. As it loses its ability to do this, components can heat up, expand, and ultimately suffer damage that could lead to a costly engine failure. 

What to do when you see a 50% warning:

• Check your owner’s manual: Opens in new tabThe best way to determine the correct oil change interval for your specific car is to consult its owner’s manual, which provides the manufacturer’s recommendations. 
• Don’t wait until it reaches 0%: Opens in new tabThe monitor continues to count down to 5% or 0%, which is the point of immediate danger, but the oil’s effectiveness has already been significantly reduced long before then. 
• Prioritize oil changes: Opens in new tabTreat the 50% warning as a reminder to schedule an oil change, especially since it’s often linked to the manufacturer’s recommended interval.