I use top tier gas. The only stations in my area with top tier are Exxon and Shell.
I have found that the off brands cause my engines to spark knock (detonation/pre-ignition/use your own words).
I have 2 Metrii. They are both 3cylinder 5speed cars. One set up primarily for MPG the other just for daily use.
Off brand fuel gives me approximately 10% less MPG in either car. So, as long as the difference in price is less than 10% ($3.50 as/to $3.25) I am actually saving money.
To address the pipeline statement above;
I have worked for the corner gas station most of my life.
Yes, all of the gas travels in the same pipeline, as does the diesel.
But, it is not all refined the same way, and there is a shuttle (cork/stopper/separator) between runs of fuel.
The off brand fuel is the 10,000 gallons before and after the shuttle to keep the bleed through from getting into the brand name fuel.
The EPA mandates what 95.5% of the fuel is made from and how it is formulated. This is how they control winter (to ignite easier and thus it burns shorter) and summer gas. The last 4.5% is left to the manufacturer. This is where the cleaners and additives make the difference. Some are better or more researched than others.
To me this makes a difference.
To other people it does not.
Some cars may see an improvement, some may not.
My Avalon cared, (but not enough to warrant paying extra)
My Metrii care,
My truck did not,
My sons Pontiac does not,
My daughters Jeep does not.
As with any of the information we receive as anecdotal evidence;
This is my perception and data,
Your Mileage May Vary
