Valero is not real popular here. I usually use Chevron or Texaco. I get about 30-40 more miles per tankful than discount stations. Probably due to less ethanol, but about 2-3 cents higher per gal. At least my Titan is Flex-Fuel. Altima is not.
I might try the Amsoil Powershot for my OPE. I use Saber Pro for my 2 cycle mix.
I think the GF-5 is a step up, at least to keep internals from rusting/corroding from the corn liquor.
I did read that some testing has changed for the GF-5 certifications... Anyone enlighten me? Something to do with the high temp wear protection..