How often should I change my oil?
On full synthetic oil in a modern engine: every 7,500–10,000 miles (12,000–16,000 km) or once a year, whichever comes first. On conventional oil, or in an older engine: 3,000–5,000 miles (5,000–8,000 km). Change the oil filter every time you change the oil.
The interval your manual gives beats the interval on the windscreen sticker
The 3,000-mile rule is a leftover from conventional oil in engines with looser tolerances. Manufacturers now publish intervals for the specific engine, and those are the numbers that matter — they are what the warranty is written against. The sticker a quick-lube shop puts on your windscreen is a business decision, not an engineering one.
Many cars built since roughly 2010 also have an oil-life monitor that counts real operating conditions — cold starts, idling time, load, temperature — rather than distance alone. If your car has one, it is more accurate than any fixed number, including the ones on this page. Reset it after each change so it keeps telling the truth.
The or once a year half of the interval is the part people skip. Oil degrades by oxidation and by collecting combustion byproducts, and both happen on a calendar, not an odometer. A car driven 3,000 miles a year still needs an annual change.
What shortens the interval
Almost every manual has a second, shorter schedule labelled "severe" or "special operating conditions". Most ordinary driving qualifies for it, which is the joke at the centre of oil changes. Use the shorter figure if much of your driving involves:
- Short trips under about 10 miles, especially in cold weather — the oil never gets hot enough to boil off fuel and water that condense into it
- Long stretches of idling or stop-and-go traffic, which age oil by time and heat while adding almost no distance
- Towing, roof loads, or carrying heavy weight
- Dust, gravel roads, sand, or salt air
- Sustained very hot or very cold ambient temperatures
- An older engine that burns or leaks oil — check the level monthly regardless of interval
Use the oil grade the engine was designed for
Interval and oil grade are one decision, not two. A viscosity such as 0W-20 or 5W-30 is printed in the manual and often on the oil cap, alongside a specification — API SP, ACEA C3, dexos, VW 504 00, and so on. A longer interval is only safe on an oil that meets the spec.
Going up in viscosity to quiet a noisy engine, or using a cheaper oil that misses the specification, shortens the safe interval and can interfere with variable valve timing and turbo bearings on engines with tight oil galleries.
How to tell it is due, without guessing
- The dipstick tells you about level, not condition — top up when low, but a full dipstick says nothing about whether the oil is spent
- Oil goes dark within a few hundred miles on a healthy engine; darkness alone is not a signal
- Gritty texture between your fingers, a burnt smell, or a milky look are all reasons to change immediately and investigate why
- A ticking or clattering top end on cold start often means oil that has thinned or a level that has dropped
- The engine oil warning light is a pressure warning, not a reminder. Stop the engine, do not drive on it