Fuel Recommended

[blewbyyou]

Headed to Bowling Green for CF8 in another week. Since I will be going through a couple tanks of gas could I just run 87 octane on the highway. Also while cruising between 70-80 mph will the AFM on the L99 take over and save me some fuel? Or should I just run 93 as I usually do?

[hunter1660]

If your car is tuned for 93 you can't,shouldn't run 87. If not 87 won't hurt it

[Royal Tiger]

You should be able to find 93 pretty much anywhere on the East Coast. I don’t know why if you normally run 93, you’d even consider running 87. If you used 100 gallons of gas it’ll cost you a whole $30-40 more.

[PalmerGA]

Your engine was designed to perform at maximum efficiency using 93 octane gas. I hear 91 works just as well but I have no experience using it. Running 87 octane will result in your ECU adjusting the fuel table and changing the engine timing to protect the engine. You will notice less power and less response and that won't change until you perform a "fuse pull" (there are dozens of thread on how to do it).

Regarding AFM: if you run 87 octane, the AFM will likely not perform as advertised and you may actually end up getting LESS fuel economy. I could never get better mileage with AFM engaged. Plus, all the automatic downshifting and switching between 4 and 8 cylinders drove me nuts... so I got a custom tune that eliminated it entirely.

Summary: IMO, you should ALWAYS run 93 (no less than 91) octane in your V8 and get rid of AFM anyway you can. These cars have 8 cylinders for a reason - use them!

[hrpiii]

Originally Posted by blewbyyou

Headed to Bowling Green for CF8 in another week. Since I will be going through a couple tanks of gas could I just run 87 octane on the highway. Also while cruising between 70-80 mph will the AFM on the L99 take over and save me some fuel? Or should I just run 93 as I usually do?

even though 87 is cheaper, your car will not run as efficient. Just run the 93, or if you really want to save a couple dollars, 89 or 91 min octane. But I would not run 87.

[Welker2]

From the Owner's Manual:

"If the vehicle has the 6.2L V8 engine
(VIN Code W) or the 6.2L V8 engine
(VIN Code J), use premium
unleaded gasoline with a posted
octane rating of 91 or higher. For
best performance, use premium
unleaded gasoline with a posted
octane rating of 93. You can also
use regular unleaded gasoline rated
at 87 octane or higher, but the
vehicle's acceleration could be
slightly reduced, and a slight audible
knocking noise, commonly referred
to as spark knock, might be heard.
If the octane rating is less than 87, a
heavy knocking noise might be
heard when driving. If this occurs,
use a gasoline rated at 87 octane or
higher as soon as possible.
Otherwise, you could damage the
engine. If heavy knocking is heard
when using gasoline rated at
87 octane or higher, the engine
needs service."

Here in Southern Nevada, you can't get 93, you can only get 91. So to answer your question, I wouldn't use anything less the 91 and I would use 93 whenever I could (as I do when I take long road trips and can find it)

[xc_SS/RS]

if its a stock tune/stock car he's fine running 87 in a pinch. this is what the Low Octane table is there for lol just don't beat on the car if you have to run 87

i do agree that to get the most efficiency/power the OP needs to run at least 91 octane with 93 preferred. if the car is tuned for 91/93 stick to that and don't run 87

running 87 vs 93 to save money is not a good idea. buy a honda if you're that concerned with your gas mileage