Synthetic vs Conventional Oil: What Ontario Drivers Need to Know

Conventional oil thickens significantly below -15°C. Synthetic stays fluid to -40°C. In Ontario, where morning temperatures regularly hit -20°C to -30°C for weeks, that means every cold start on conventional oil involves your engine running with inadequate lubrication for the first 30 to 60 seconds. Over thousands of cold starts across Ontario winters, that adds up to measurable engine wear.

Cost Comparison

Ontario shop prices in 2025: conventional oil change $50 to $80, synthetic $80 to $130. But conventional needs changing every 5,000 to 8,000 km while synthetic goes 10,000 to 15,000 km. At 20,000 km/year, the annual cost difference is roughly $15. For that $15 you get dramatically better cold-weather protection.

DIY is even cheaper: a 5L jug of Mobil 1 synthetic costs about $45 at Canadian Tire and a filter is $10 to $15.

When Conventional Is Fine

Older vehicles (200,000+ km) that have always run conventional may develop small leaks if you switch. High-mileage synthetic formulas with seal conditioners (Mobil 1 High Mileage, Pennzoil Platinum High Mileage) address this.

Viscosity for Ontario

Most modern vehicles specify 0W-20 or 5W-30. The first number is cold-weather flow — lower is better. A 0W-20 synthetic is ideal for Ontario winters. Check your owner's manual and use what it specifies. Brand matters less than matching the spec: Mobil 1, Castrol Edge, Pennzoil Platinum all meet the same API standards.

For more on winter engine care, see cold weather and your engine and our fall maintenance checklist.