This week's tip: How To Save Money at the Gas Pump
1) Before filling up, check with the manufacturer to see what octane rating is recommended for your engine. This information can usually be found in the owner's manual, or a quick call to your local dealer can usually resolve it. If your vehicle has an aftermarket engine, consult your engine builder for the recommended octane.
2) Use only the recommended octane. No more, no less. A lower octane may cause problems for your engine. A higher octane may cost you more with no benefit, and may even cause problems for your engine. You're not doing your engine a service by going for a higher octane than what's recommended.
3) Make sure you understand what the numbers mean and use the right rating. Different countries and different parts of the country rate gasoline differently.
Octane rating - Wikipedia, the free encyclopedia
4) Filling up after dark when the ambient temperature is cooler may help stretch your gas dollar because cooler gas = denser gas = slightly more gas by volume.
5) Be wary of small gas stations that advertise low prices. I recommend patronising a high traffic station even if their prices are slightly higher. This is because if gas sits for a long time, it starts collecting water. A busy station has quicker turnover and tends to clean out their in-ground filter more often. A few bucks saved at the pump may cost you much more for repairs as the result of using bad gas.