How Often Should You Change Synthetic Oil?

Most modern cars running full synthetic oil can go 7,500–10,000 miles (12,000–16,000 km) or about 12 months between changes—whichever comes first—provided you follow the vehicle’s oil-life monitor and use oil that meets the automaker’s specification; shorten that to roughly 5,000–7,500 miles or 6 months if you tow, make frequent short trips, drive in extreme temperatures, or in dusty conditions. This article explains how manufacturer guidance, driving habits, and oil-life monitoring systems determine the right interval for your engine.

What Automakers Recommend in 2025

Automaker schedules—and the on-board oil-life monitors (OLMs) that implement them—are the most reliable starting point. While specifics vary by brand, engine, and market, most late-model vehicles now permit longer intervals with synthetic oil when driven under normal conditions.

• Typical mainstream guidance: 7,500–10,000 miles (12,000–16,000 km) or 12 months with full synthetic, following the OLM.
• European “long-life” programs: up to 10,000–15,000 miles (16,000–24,000 km) in North America when approved long-life oils are used; some European-market schedules extend further under flexible servicing.
• High-performance/turbocharged or direct-injection engines: intervals may be on the lower end of the range due to heat and potential fuel dilution; always check the exact spec in your manual.
• Older vehicles or those without OLMs: conservative intervals of 5,000–7,500 miles (8,000–12,000 km) with synthetic are common, but follow the owner’s manual if it specifies otherwise.

Ultimately, your owner’s manual rules: the OLM algorithm and the oil specification listed there are tailored to your engine’s design and emissions system.

How Your Driving Changes the Interval

Driving conditions can shorten or extend oil life. Automakers call harsher use “severe” or “special” service, and it often triggers earlier changes even with synthetic oil.

• Frequent short trips (engine rarely fully warms up)
• Stop-and-go city driving or extended idling
• Towing, hauling, or mountain driving
• Very hot or very cold climates
• Dusty, sandy, or unpaved roads
• Track days or spirited driving

If your routine matches any of these, consider changing synthetic oil closer to 5,000–7,500 miles (8,000–12,000 km) or as indicated by your OLM under “severe” service settings.

Oil-Life Monitors: Understanding the Percentage

Most 2010s–2020s vehicles estimate oil degradation with an OLM. It doesn’t just count miles; it factors temperature, idle time, trip length, load, and more to recommend change timing.

1. Use the OLM reading as your primary cue; change the oil when it reaches the threshold your manual specifies (often 5–15%).
2. Follow “whichever comes first”: time (often 12 months) can trigger a change even if miles are low.
3. Reset the OLM after every oil and filter change so future estimates remain accurate.
4. If you add significant oil between services, still follow the OLM or the time limit; topping up doesn’t reset additive depletion in the sump.

Think of the OLM as a usage-based maintenance tool—more precise than fixed-mileage rules, provided you reset it and use the correct oil.

Mileage vs. Time: Why Months Matter

Even when you don’t rack up miles, oil ages. Short trips can leave moisture and fuel in the crankcase, and additives deplete over time. That’s why many manufacturers specify an annual change maximum. If you drive very little or mostly make brief errands, prioritize the time limit and consider more frequent changes.

The Right Oil and Filter Make the Interval Possible

Extended intervals assume you’re using oil and filters that meet the engine’s requirements. Labels and approvals matter more than brand names.

• Match the viscosity and approvals in your manual (for example: API SP, ILSAC GF-6A/6B, ACEA specs, or OEM approvals such as GM dexos1 Gen 3, VW 504 00/507 00, BMW Longlife, Mercedes-Benz MB 229.5/229.52).
• Use a high-quality filter rated for extended intervals; some budget filters are intended for shorter drains.
• For turbocharged and direct-injection engines, the correct low-ash or LSPI-resistant oil is crucial for durability.

If the bottle doesn’t list the exact specification your manual calls for, choose one that does; the right approval is what supports longer intervals and protects your warranty.

When to Change Sooner: Practical Warning Signs

Beyond mileage and the OLM, certain symptoms hint that your oil may be degrading faster than expected.

• Noticeable fuel smell on the dipstick or a rising oil level (possible fuel dilution)
• Abnormally dark, gritty oil soon after a change, or metallic sheen
• Louder engine operation on cold start, new ticking/knocking, or increased turbo whine
• Frequent short trips with condensation “mayonnaise” under the oil cap
• Dashboard warnings related to oil pressure or engine health

If any of these occur, err on the conservative side and schedule an earlier oil and filter change, then re-evaluate your interval.

Simple Maintenance Habits to Protect Your Engine

A few quick routines can extend engine life and keep your interval on track.

1. Check oil level monthly (and before long trips) and top up with the same spec/viscosity.
2. Replace the drain plug washer and torque to spec to prevent leaks.
3. Always change the filter with the oil, and verify the old gasket isn’t stuck to the housing.
4. Reset the OLM and record the mileage/date; keep receipts for warranty documentation.
5. If your driving pattern changes (more towing, more short trips), reassess the interval at the next service.

These steps help ensure your OLM remains accurate and your engine gets the protection the manufacturer intended.

Bottom Line

With full synthetic oil, most modern vehicles safely run 7,500–10,000 miles or 12 months between changes under normal use, guided by the oil-life monitor. If you drive in severe conditions, shorten the interval. Always use oil and filters that meet your vehicle’s exact specifications, and document your services to protect your warranty.

Summary

Change synthetic oil every 7,500–10,000 miles or annually for typical driving, deferring to your vehicle’s oil-life monitor and owner’s manual. Severe conditions call for 5,000–7,500-mile or 6-month intervals. Use the exact oil spec and a quality filter, reset the OLM, and keep records. Mileage and time both matter—whichever comes first is the rule.