Conventional motor oil is typically good for 5,000 miles or 6 months, while synthetic oil can last 7,500 to 10,000 miles or 12 months. However, this is a general guideline, and the actual interval depends heavily on your driving habits, the vehicle's age, and the manufacturer's specific recommendations found in your owner's manual. Following the correct oil change schedule is critical for preventing engine sludge, reducing wear on internal components, and maintaining optimal performance.
The "best by" date for motor oil is not a single number. Think of it as a fluid lifespan influenced by several factors:
- Driving Conditions: Short trips where the engine doesn't fully warm up (known as "severe service" driving) cause moisture and fuel contaminants to accumulate in the oil more quickly. This necessitates more frequent changes, often at the lower end of the recommended range.
- Oil Type: Synthetic oil is chemically engineered to be more resistant to thermal breakdown and oxidation than conventional oil, which is why it has a much longer service life. Many modern vehicles require synthetic blends or full synthetic oils.
- Vehicle Age and Model: Older engines with more miles may have worn seals and generate more contaminants, suggesting a shorter interval. Always prioritize the oil change schedule specified by your vehicle's manufacturer.
Many newer cars are equipped with an Oil Life Monitoring System that calculates the remaining life of your oil based on engine revolutions, temperature, and load data. This is often the most accurate method for your specific driving style.
| Vehicle Age / Oil Type | Standard Interval (Miles) | Severe Service Interval (Miles) | Time-Based Limit (Months) |
|---|
| New Car (using Full Synthetic) | 7,500 - 10,000 | 5,000 | 12 |
| Average Car (using Synthetic Blend) | 5,000 - 7,500 | 3,000 - 5,000 | 6 |
| High-Mileage Vehicle (over 75k miles) | 3,000 - 5,000 | 3,000 | 6 |
| Classic Car (driven infrequently) | Varies by use | N/A | 6 (regardless of mileage) |
The safest approach is to check your oil monthly. Pull the dipstick; if the oil is dark black and gritty, or the level is low, it's time for a change regardless of the mileage.
