Every 5,000 km, no matter what. That was the rule for a long time, and plenty of people still follow it. Most cars built in recent years call for something different, sometimes longer and sometimes, depending on how you drive, not much longer at all.
Start with the owner's manual
The right answer for your car is in the maintenance section of the owner's manual or the manufacturer's maintenance guide. Most are online if you've lost the book. It gives you two limits: a distance and a time. Change the oil at whichever comes first.
Many modern cars list intervals somewhere between 8,000 and 16,000 km under normal conditions, with a time limit that's often 12 months. A car that only does 6,000 km a year still needs at least one oil change a year. Oil breaks down and collects moisture and acids even when the car mostly sits.
Normal versus severe service
Most manuals list two schedules. The normal one is the number that gets quoted. The severe one applies to more drivers than you'd expect. Conditions that usually count as severe include:
- Mostly short trips, where the engine doesn't fully warm up
- Stop-and-go traffic and a lot of idling
- Very cold or very hot weather
- Towing a trailer or carrying heavy loads
- Dusty or gravel roads
- Delivery, taxi or rideshare driving
The severe schedule is often a lot shorter than the normal one. Each manufacturer defines these conditions a little differently, so read the fine print in yours.
Why Toronto driving often counts as severe
Think about an ordinary week here. A 5 km run to the grocery store. Forty minutes on the 401 to cover 15 km. A January morning at −15 °C with the car idling in the driveway while the windshield clears. That's short trips, stop-and-go, cold starts and idling, which is most of the severe list.
Short trips in the cold are the hardest on oil. Every cold start produces condensation, and a little unburned fuel gets past the piston rings into the oil. On a long drive the oil gets hot enough to drive most of that off. On a ten-minute trip it doesn't, so the water and fuel stay in the oil and thin it out. Over a winter of short trips, oil can wear out well before the kilometres say it should.
If most of your driving looks like that, follow the severe schedule, or at the very least don't stretch past the normal one.
Oil life monitors
Many newer cars don't use a fixed interval. An oil life monitor tracks things like engine revolutions, operating temperature and trip length, then counts down a percentage. These systems are generally good, and they already factor in a lot of the severe-service conditions above, so it's reasonable to follow them.
Two cautions. The monitor has to be reset after every oil change, or it's counting from the wrong starting point. And it estimates the condition of the oil; it doesn't measure how much is in the engine. A car can be a litre low with 60% oil life showing on the dash.
Check the level between changes
Some engines use a bit of oil in normal operation, and manufacturers allow for it. Check the dipstick once a month or every couple of fill-ups, on level ground, with the engine off for a few minutes. If it's at or near the low mark, top up with the oil your manual specifies. Some newer cars don't have a dipstick and show the level in the instrument cluster instead. If you find yourself adding oil regularly, mention it at your next service.
Synthetic or conventional
| Type | What it is | Where it fits |
|---|---|---|
| Conventional | Refined from crude oil | Older engines that specify it, and easy driving |
| Synthetic blend | Conventional oil mixed with some synthetic base oil | A middle step for engines that allow it |
| Full synthetic | Base oils engineered for more consistent properties | Most newer engines, and many require it |
Full synthetic flows faster on a cold start, holds up better at high temperatures and resists breaking down. Many modern engines require it, especially turbocharged engines and those that call for thin oils like 0W-20. Your manual lists a viscosity, such as 0W-20 or 5W-30, and often an approval or specification as well. Match both. The right viscosity without the required approval isn't the right oil.
If your engine allows conventional oil, synthetic is still fine to use. It doesn't let you skip the time limit, though. If you're not sure which schedule fits the way you drive, ask at your next oil change and we'll go through it with you.
