I was in a conversation with some friends about whether using lower octane gas is OK for a performance car. By OK I mean will it cause engine damage long or short term? I dont think its a great idea to use 87 or whatever but just question in theory.

I personnally use 91 octane, thats the best I can get in my area but I was under the impression that in these newer cars with computers that it will adjust to the lower Octane gas and maybe not run as good but wouldnt do any harm.

Basically they were telling me that it would knock and cause engine damage.

?

 

This gets hotly debated at least once a month, especially now with the price of fuel. The most recent was maybe three weeks ago.
Try a search this forum in the red banner in C5 Tech and see what you come up with.
You'll find plenty to read...

 

If your going to use a lower grade gas you better put an additive in the tank also. These cars need the high octain to run or they will knock unless you have it tuned to run the cheaper gas. This engine is a high performance engine so you need at least 91 octain. Gary.

 

I doubt it would hurt anything. We have knock sensors for a reason...it will just pull timing which affects your power.

 

We have high compression. high performance engines which require a minimum of 91 octane to run at optimal performance.. Anything less causes damage to the engine.. The knock sensors only help to a minimal extent (minor pinging). If you run 87-89 in the tank you will hear the dreaded "coffee can full of marbles sound.. What really blows my mind is that there is only a .10 cent difference between 89 octane and 93 octane here in Texas.. Thats $1.80 cost difference per tank of gas. WTF???!!! Is $1.80- $2.50 per tank worth the savings?? No fricking way.. If you guys are so cheap/ I can make a budget for you, so that you can shave off an extra $2.00 a week for premium gasoline Good Gawd

 

 

The owner's manual says that 91 or 93 octane is recommended. However, it also says that you may use as low as 87 octane, with the only consequences being a slight loss in power (i.e. computer pulls timing).

With that said, I've never run anything less than 93 octane in my Z.

 

I agree that you might as well put in the better stuff if you have a high performance car.

Somebody just ask me do you have to? I said no and it started a arguement.

Sounds like two schools of thought.

 

I usually run 93 but when I am going on a trip I will dump in 87. I figure 1500 miles of continuous operation on cruise at 70 or so is not going to hurt it.

 

This is a Great Thread for owners of any high performance car, not just 'Vettes!! I'll throw my .02 in........

If the specs call for 91 octane (minimum), do not, I repeat, DO NOT run 87 in your car! David 426 mentioned the "dreaded coffee can sound" of marbles etc. coming from the engine with use of 87 - 89 RON fuel. Problem is, with today's advanced engines, including GM's high performance units, we'll probably never hear anything. If we do, it'll be too late. Yes, the ECM will "pull timing," but that may not be enough. 91 octane burns at a higher temperature than 87 or 89. Therefore, 91 is much more satisfactory for higher compression engines. That way, early detonation due to compression will not occur prior to spark ignition. Using 87 octane in place of 91 will almost guarantee reduced power due to partial or complete ignition of the fuel air mix due to compression (not spark) and a poor flame front over the top of the piston. Additionally, it's a good way in the long run to put a hole in the top of a piston.

So, use the right fuel for your car - - it'll save you BIG $$ in the long run.

Steve

 

If you want to save $$.. You are better off using the generic Auto Parts Store Brand of conventional oil. It will do a lot less damage in the long run than 87 octane