You CAN use it, for sure. I use it myself from time to time in the winter. But the car performs as it should when you use the recommended octane. And to be clear, you can change octanes or brands at will, they all mix together just fine.

Ok I filled up with 91 today. I feel a lot better too haha. Will I notice a difference after using 87 for almost 9 months?

The higher octane protects the motor from knocking. You can run a lower octane, but your car will trip out when you get on the gas pedal.

A lot of states other than CA have 93 instead of 91. You can find 100 at some locations throughout the SF Bay Area, some in San Jose.

Where can I find 91+ octane? I'm in San Jose also I've only seen 91s tho

^You don't need it foo lol

The saleman told you 'regular gas' to make the sale. Read the manual or the info printed on the gas door.

most of my driving is on trnpk @ 70 mph...I have had the initial timing boosted by +2 degrees....I have run 89, 91. 92, 93 all on measured tests of exactly 220 miles, (same trip) I have found that my car runs just great on ANY of the above.. it never knocks or pings and always get 27.2 mpg. no matter what.... the computer know best and it will retard if necessary..the differnce in price here in So central Pa. is.....3.75 reg 87, 3.87 mid grade 89 and 4.09 for 92 which is avail at my loc.

so cost for fill up with 89 octane (20) would be 77.40 or for the 92 would be 81.80 its YOUR CHOICE...my car does not care and runs like new always. I would NOT run 87 at any time.

You could alternate between mid and premium , but never ever low grade !!

I tried 89 once and did notice the loss in performance. With premium, it just goes and gives you that rush when you step on it. But with 89, it seemed to hesitate going faster

i have no problems at all running on mid grade. if anything it stops me from romping on the car all day

Exactly, you don't need it. You can find 100 at the 76 off of Almaden Expressway near Foxworthy, but unless your car is tuned to run 100, you're not going to make much power with it and you'll just be wasting the money. There are a few more with 100, I forget where though.