questionsdoes it matter what gas "brand" i fill up with?

vote-for21vote-against
vote-for12vote-against

From what I understand, the difference in brands is merely a difference in additives.
The key is to purchase fuel at a station that has good volume, so as to get fresh stuff with less crud in it.
Bonus is that's usually the lowest cost option.

j5 j5
vote-for3vote-against

Funny I would have said no that is an old wives tale 2 days ago, but we filled up with Casey's gas and not 5 highway miles later I look down and the check engine light comes on. We pull over and the instructions say check the gas cap. I made sure it was tight(something I have never had an issue with). When I got home we googled it because the the light did not go off. The internet said battery cap and to unhook the battery for 10 minutes, we did for longer. The light came back on. The light has been on we got at least 2 tanks of gas from our Shell since. Last night I unhooked the battery and the light did not come back on.

So an unexpected yes from me.

vote-for5vote-against

@j5: Truth in that the gasoline base is exactly the same brand to brand. Then each retailers adds their proprietary additives to their gas. How much of that is beneficial? How much is marketing snake oil? I don't know. I'm not a chemist. However, General Motors (and other manufacturers) have recognized the benefits of "top tier" gasoline, or retailers that offer a final product that EXCEEDS standards that the EPA regulates. Here's a list of retailers that are recognized for offering "top tier" gasoline:
http://www.toptiergas.com/retailers.html

vote-for4vote-against

I fill up with regular and then add a container of Marvel Mystery Oil in the gas tank every 5 tanks

vote-for3vote-against

Gas is gas, it's all the same chemically. In some markets (like mine), virtually all the gas sold at any station within a 75-mile radius comes from one refinery. All the "extra special mileage-boosting engine-cleaning" crap is added at the pipeline depot outside of town.

I buy 87-proof and add a bottle of STP every 10th tank. So far my 20-year old Volvo doesn't seem to care what logo is on the pump.

vote-for4vote-against

No. Chances are good that all of your local gasoline comes from the same distributor. YMMV (sorry, I had to throw that in at the end).