Yes I also trust costco 91 because of supply turnover. But the lines are always so long, I'd rather pay the extra few cents to not wait in lineYou have Costco’s in Tucson and the 91 fuel there is decent
I was watching a Porsche Workshop on YouTube last night and presenters were stressing the importance of using top tier fuel for engine health. I had never heard of top tier fuels. Service stations that use top tier fuel is supposed to contain additives that minimize carbon buildup in the engine. I have always purchased my gas from discounters such as Wawa, 7-11, Sheetz, and Liberty and none of those were on the top tier list, however I noticed that Marathon was. Marathon usually has fuel prices similar to the ones I use. I may be changing where I buy fuel. https://www.toptiergas.com/gasoline-brands/
Mainly via improved engine control software combined with exacting oil specifications, Ford, along with the automotive industry in general, slew the LSPI dragon long ago. Pretty much the entire automotive industry has embraced the small-displacement turbocharged revolution, yet when was the last time you heard about catastrophic engine failure of a stock engine due to LSPI? This is despite the fact the overwhelming majority of owners use the lowest octane fuel allowed.Not sure low speed pre ignition is possible with automatic transmissions, but I figure, it's only a few cents more per gallon, and gas is expensive either way.