Synthetic vs. Conventional Oil: What You Really Need
Is synthetic oil worth the extra cost? We break down the facts and myths about motor oil so you can make the right choice for your vehicle.
Walk into any shop and you'll be offered a choice: conventional, synthetic blend, or full synthetic. The price difference is real — but so is the difference in performance. Here's what actually matters when choosing motor oil for your vehicle.
What Is the Difference?
Conventional motor oil is refined from crude oil. It does the job, but it contains impurities and breaks down faster under heat and stress. Full synthetic oil is engineered at a molecular level — it's more uniform, more stable under temperature extremes, and resists breakdown longer. Synthetic blend falls in between: conventional oil with some synthetic added.
Does Your Car Require Synthetic?
Many modern vehicles — particularly turbocharged engines, European cars, and vehicles with variable valve timing — require full synthetic oil. This is not a recommendation; it's a specification. Running conventional oil in an engine designed for synthetic can cause oil starvation, increased wear, and voided warranty coverage. Check your owner's manual or the oil cap — if it specifies 0W-20 or 5W-30 full synthetic, that's what it needs.
Turbocharged Engines Need Synthetic
Turbochargers spin at up to 150,000 RPM and run extremely hot. When you shut off the engine, oil circulation stops but the turbo continues spinning and radiating heat. Conventional oil can break down and coke — turning into carbon deposits — in the turbo bearing housing under these conditions. Full synthetic resists this. On turbocharged engines, it is not optional.
Oil Change Intervals: Synthetic vs. Conventional
Conventional oil typically lasts 5,000–8,000 km between changes. Full synthetic can go 10,000–15,000 km depending on the vehicle and driving conditions. The longer interval offsets some of the higher cost of synthetic. If you do frequent short trips, city driving, or towing, change intervals should be shorter regardless of oil type — short trips don't allow the engine to fully warm up, which accelerates oil degradation.
Can You Switch From Conventional to Synthetic?
Yes. The concern that switching would cause leaks in older engines is largely a myth with modern vehicles. Synthetic oil is compatible with conventional and won't cause seals to fail in a well-maintained engine. If the engine has significant sludge buildup from years of conventional oil, an engine flush before switching is worth considering.
What About High-Mileage Oil?
High-mileage oils — typically for vehicles over 120,000 km — contain seal conditioners that help maintain aging gaskets and reduce minor leaks. They're available in both conventional and synthetic formulations. If your vehicle is burning a small amount of oil or showing minor seepage, a high-mileage synthetic is worth considering at your next change.
Final Thoughts
If your vehicle requires synthetic, use synthetic. If it doesn't, a synthetic blend or conventional oil will do the job. When in doubt, check the owner's manual — or book an oil change in Mississauga and we'll look it up for you. Not sure what your vehicle needs? Call us at (905) 624-4646 and we'll check in under a minute.
