cagey444

I've been running my 2008 Bullitt on 91 octane gas for about 32K miles now. However, we all see where gas prices are going now and I put about 70 freeway miles per day, 4 days a week. After all this time running premium, would it create problems to begin running regular unleaded (87 octane). The Bullitt is straight off the floor, no mods at all.

Sorry if this is a dumb enquiry - I've checked the boards, but haven't had much success in an answer. 20 cents a gallon difference adds up when you're filling your tank twice a week.

Thanks

Franchi

No, it won't make a difference in a stock engine. Fill her up and let it rip!

cagey444

Great, thanks. Guess I'm also curious about performance / knocking, etc. I hate to give my baby anything but the best.... but my wallet is crying.

Thx.

Franchi

It should even say in your owners manual that it recommends 87 octane.

Difference in gas won't affect a stock engine by any means, although there IS a difference between gas statiosn. Shell, Sunoco, Exxon and Mobile are generally considered better then brand X gas stations.

Only when do you get into a tuned engine ( Like with a SCT Xcal 3 or Diablosport ) that is specifically tuned for an octane of gas do you need to run it. Or running forced injection on MASSIVE PSI.

cagey444

In this case, the "Brand X" gas I'm running is Coscto. (Either that, or Chevron in a pinch. Never anything else). I have heard varying opinions on Costco's gas quality - some good, some bad.

TRUEBLUE3934

As long as the owner's manual doesn't recommend a higher octane fuel, you have no benefit from running it. A car must be tuned for higher octane fuel in order to benefit from it.

I have been running 87 octane in my wife's 2002 Miata nearly every tank since new (it suggests 91+oct) and it runs fine with it. When we throw bags in the trunk and head to the mountains for the weekend, I run 93oct to prevent any chance of pinging under heavy load.

Franchi

That's usually the case you have when discussing anything related to gas stations with people. Some good, some bad. Long as the car runs well and doesn't hurt the wallet TOO bad, do whatever floats your boat! :-)

cagey444

Thanks for suggestions. I will begin putting 87 in starting today, probably at 1/2. Owners manual mentions that 87 will work, but if it starts to ping or knock, then I'll have to rethink it. It is a Bullitt after all and if I can't get the "jump" I need on the freeway on-ramps, then knocks aren't acceptable.

Gas prices aren't going to be very amusing in the next few months.

Franchi

lol Yeah tell me about it, I get close to 10 mpg in the 06 GT.

akiba17

The 08-09 Bullitts come with dual knock sensors, meaning it can tell what octane you have and adjust the tune accordingly, you will lose a bit power, not much though and you will damage nothing. Your best bet is to let your fuel get low then fill it up with 87 octane.