91

I came from a car that only wanted owners to use 91 octane. I noticed the Genesis states that you can use 87 but 91 is recommended? What are you using? For those that are using 87, have you experienced any negative outcome such as knocking?

ok, w/ gas prices soaring (4.29 for regular where i live and 4.50 for premium) at the pump and no end to these high prices in the near future, what are you guys using? i have always used premium (91 octane) but now i'm considering 87. just wondering if you will feel a difference in the...

Just drove home in a 4.6 and have 150+ miles to figure out what Octane I'm going to use in the beauty. A Sunoco fan with too many options (89,91 or 93). Any thoughts (mileage, performance, engine care ...) from the experienced?