87 octane, usually from Sam's Club - ALways gotten good gas there and cheaper than anyone else. When Sam's not available then Shell or another good quality station.....on Interstates I like TA or Petro.
87 octane recommended but less octane required at altitudes so in mountains have run 85. Come down the hill and next tank 89 or 91 then back to 87.
2008 Pilot stated HP ratings with 87 octane and Acura MDX was rated ah higher HP but with premium gas (89 or 91). Same engine, advertising pitch.
Pilot manual recommended premium for towing but 87 for everyday.
Not sure if newer engine has different ratings for HP but will look into that.
Best mileage on the recent trip out west was 29 mpg in regular mode, all above 9000 feet altitude with 85 octane gas.
Now that gas prices have risen once again in CALI, I typically use gas on base which is fairly lower priced than the outside world. Realizing this is gas has no detergents whatsoever I use the higher octane fuel from Chevron to get the better gas mileage as well as help to clean the system. Its just my personal preference, but the numbers are great when my girl gets the Super Unleaded vs. Mid/Regular.