What brand of gas do you use?

[Ray]

The Boxster engine is designed to take a higher octane ... it has a higher compression. I use Sunoco 94

[Gary in BR]

I use Chevron or Shell.
I prefer Chevron but there are more Shells around here.

[986Porsche986]

Here in Phoenix the highest Octane we can get is 91. A few stations sell some 105 racing, but I have read many forums that say to stay away from that stuff for the Boxster. I use Chevron Premium about 80 percent of the time and QT the other
18% (2% of the time is from Costco or some other station only when I am forced to)
When I first bought the Boxster, I asked my service tech at Porsche what she would recommend for fuel. she pretty much said 93 octane Chevron is ideal, but because we can get only get 91 max octane here in Arizona, that it what I use. She is also
the one who told me about a study of all the big German motor companies, Porsche,
BMW, Mercedes who tested different fuels for their consistency and performance and QT was right up there with Chevron. Nice thing about QT is that their prices are close to Costco prices.

The other thing, someone once told me to avoid filling up at a station that is
getting their new gas pumped into their storage tanks because it causes any sediment in the storage tanks to get stirred up and possibly can shorten the
life of your fuel filter. Not sure how true this is, I would think that the stations
have several filters in place, but if I do pull into a station and they are getting
fresh fuel pumped in, I drive right out and go to another or I wait and come back the next day. I never let my boxster get below 1/4 tank.

[Kirk]

I believe a lot of the race gas is leaded, which is why you want to stay away from it. The lead will definitely screw up your O2 sensors and I believe your cats too.

I just buy what's cheap. Once in a while I run my tank low and then fill up with Shell V-Power California 91 Octane Piss Water Gas. I figure with all the fancy detergents and injector cleaners in the expensive gas a tankful now and then will help keep me humming along. Never used Chevron around here as it's the most expensive...