I try to share common questions I am asked on a regular basis, one of those is about gas. We all know we need it, the three elements of internal combustion motors are fuel,air and spark. The one that costs the most in this equation of course, is gasoline.
To some the goal of finding the "cheapest" gas is a weekly mission which includes memorizing local prices. The questions I am asked are: Is one gas better than another? Should I buy a higher octane gas? and What gas do you use? These are all great questions and all have easy answers.
First, not all gas is created equal. Actually, only a few are distilled for specific companies. Take Chevron and Shell, both actually manufacture their own gasoline. Yes, Chevron is expensive but Chevron is the only U.S. company to ad detergent to all octane levels (known as Techron). Shell has also stepped up by adding "V-Power" additive, but only to it's premium gas. Texaco will soon be adding Techron as well in the near future. These additives help your car with running smoother and keeping engine internals clean among other things.
Decisions, decisions
Should you buy a higher octane than what your car recommends? No, save your money for a new air filter for better gas mileage. Engines are designed for specific octane gas and using a higher octane is actually a waist in most engines. Octane refers to the knock resistance (anti-knock rating). If your car doesn't have "knock" with the fuel you use, there is no need to step up to a higher octane.
What gas do I use? The 6.0 in the GTO requires 91 octane. The Goat gets either Chevron with Techron or the Shell with V-Power (surprise!). The additive helps keeps the valves and cylinder walls clean of deposits. After seeing torn down motors which have used standard and detergent fuel, I have seen the difference and what these companies say are true. My little Mazda B2300 pickup (aka PutPut) also gets one of the two above even though it takes 87.
With some of the "cheap" gas stations by the time you pay the "ATM fee" it ends up costing the same as the good stuff. Or what about the person that burns a dollar in gas to make it over to the cheap station only to end up saving .40¢ cents on the tank! Look at it like this: say Chevron is $3p/gal. and USA is $2.95p/gal. and you buy 10 gallons. This means you save a whopping .50¢ cents and chances are you will get less mileage out of that cheap tank than you would from the good. Test it for yourself! I have found by using higher quality gasoline you can gain 20-30 miles per tank, that's $5 bucks savings right there.
Happy Motoring,
Lance
I thought it should be mentioned that all gasoline starts out as a fairly standardized formulation. What sets brands apart are the additives that supplement the blend. So using a cheaper gas isn't necessarily bad for your car - Techron detergent can be purchased at most autoparts stores for around $6 /bottle. One could run it through quarterly to maintain their fuel system.
Re: octane selection; In my experience it really depends on the car. If there are readers that have pre-82 cars that are sans ECM, [computer controlled], they can get more power [if desired] by tuning [timing] their car to run with the higher octane. For example I have a 69 Firebird that I've had to de-tune to accept todays lower 91 octane, [sadly I lost power]. The point is that older cars are adjustable/tuneable.
Also some ECM's [or German DME's] use multiple knock sensors that work with the DME to allow a variance in octane content. My Porsche requires 98 octane that's obviously not available in this country. When the DME senses a knock it retards the timing. If I run a mix of 91 & 100 octane race gas there's a noticeable difference, [smoother & more power].