At the pump, the question comes back with every fill-up: regular, mid-grade or premium? Premium costs several cents more per litre, and many drivers pick it thinking they’re “treating” their engine. In the vast majority of cases, it’s wasted money. Here’s how to know what your vehicle actually needs.
What does the octane rating mean?
The octane rating measures a fuel’s resistance to auto-ignition — its ability not to ignite too early under the engine’s compression. In Canada, you generally find three grades: 87 (regular), 89 (mid-grade) and 91 or more (premium). A higher rating doesn’t mean a “better” or “cleaner” fuel: it simply means the gas withstands stronger compression without igniting prematurely. That’s all.
When is premium actually necessary?
It all depends on what your engine asks for. There are three cases:
- Premium required. Some high-performance or turbocharged engines are designed for high-octane fuel. If the owner’s manual says “premium fuel required”, you must use premium: otherwise the engine can lose performance and, over time, suffer wear.
- Premium recommended. Other vehicles say premium is “recommended” without being mandatory. On regular, they adjust and run without issue, with at most a very slight performance dip you won’t notice day to day.
- Regular is enough. The vast majority of vehicles are designed for 87. Putting premium in them brings no gain: no power, no efficiency, no longevity.
To know which category you’re in, one document is authoritative: the owner’s manual (or the label inside the fuel door). Trust it, not the received wisdom.
The myth: “premium cleans the engine”
It’s probably the most widespread belief — and it’s false. A gasoline’s cleaning power doesn’t come from its octane rating but from the detergent additives it contains. At a retailer that meets the Top Tier standard, regular 87 and premium contain the same level of detergents. In other words, paying for premium in the hope of “cleaning” your engine changes nothing: if cleanliness is your concern, look for detergent additives, not octane.
How much does unnecessary premium cost?
Premium commonly sells for several cents more per litre than regular. For a vehicle that doesn’t need it, that gap becomes pure expense, fill-up after fill-up, with no benefit. Over a year, the difference can add up to a substantial amount — the equivalent of several free fill-ups. To compare actual prices around you, see the average prices by region or the price map. And to understand what makes up each litre, read our guide on gas taxes in Quebec.
Frequently asked questions
Is it risky to put regular in a car that “recommends” premium?
No, as long as the manual says “recommended” and not “required”. Those engines adapt automatically to regular. If the manual requires premium, though, you must comply.
Does premium give any car more power?
No. An engine designed for 87 draws no extra power from premium. The performance gain only exists in engines specifically built to exploit a high octane rating.
Is alternating between regular and premium bad?
For an engine designed for regular, alternating does no harm — but brings nothing either. The simplest and cheapest approach is to stick with the grade the manufacturer specifies.