Updated 2026-05-23 · 5 min read
When to fill up to pay less
Gas isn't priced randomly. There are weekly patterns, hikes before long weekends, and a well-documented "Wednesday" effect. Here's what we can predict — and what we can't.
Approximate rules
📈 Wednesday noon to Thursday evening — Retailers often adjust upward mid-week. Avoid if possible.
📉 Sunday and Monday morning — Often the best prices of the week, especially in Greater Montréal. Retailers let prices drop before pushing them back up.
⚠️ Thursday before a long weekend — Sharp hike. Everyone anticipates holiday travel. Fill up the Monday before.
🌡️ April (transition to summer blend) — More expensive summer formulation pushes prices up 4–10¢/L. Unavoidable, but useful to know it's not a scam.
🍂 October (return to winter blend) — Conversely, prices usually drop when winter formulation arrives.
⏳ The big event of 2026: September 8
On September 8, 2026, the federal fuel excise tax suspension ends. Gas will jump ~10¢/L and diesel ~4¢/L instantly. A full tank on September 6 or 7 is the most profitable single decision of the year.
What we can't predict
Many factors escape simple rules: geopolitical conflicts (Hormuz, OPEC+), refinery outages, hurricanes in the Gulf of Mexico, USD/CAD swings. Beware of "precise weekly predictions" online — they don't hold up better than a coin flip.
Our approach at InfoGas: observe relative patterns ("this station is cheaper than its zone today") rather than predicting absolute prices. Upcoming smart alerts will automatically detect anomalies without guesswork.
30-second tactic
- 1.Don't let your tank drop below 1/4 — it forces a Wednesday fill-up.
- 2.Do a half-tank on Sundays, top up mid-week only if you're running on fumes.
- 3.Before a known long weekend, fill up the Monday before.
- 4.Watch the InfoGas homepage: our 3 recommendation cards already factor time-of-day + day-of-week.