O.k. I am restoring a 95 Z28. I am the third owner. I had a guy do some work on it when I got it to pass insp. He said it is O.K. to run reg. It has the Lt1 eng. Now I have a friend who owns a corvette retail shop. He says to run prem.gas..What do i do. I have only fulled up twice with reg. And have no idea what was put in before I had it. And it is not about the money.. I just want todo the best thing for the car. Do I keep it at reg. or change? And If I keep it will it hurt anything? Or do I change, and would that hurt anything? The car has 153300 miles on it. I will only be driving it once or twice a week, maybe more in the summer.What do I do.

 

ok in the poll above. The top answer is reg.
the bottom is prem.

 

Read the Owner's Manual:
Its simple - to get the performance your engine was designed for, you need to run premium fuel. If you run regular grade, you will get detontation, the knock sensor/PCM will pull ignition timing, and the engine power will be reduced. Running regular grade fuel will not "hurt" the engine - the knock sensor protects it. But it won't produce power.

Changing from regular to premium fuel will not "hurt" anything either.

Its not something that is determined by a "poll"....it determined by the engineers who designed the engine.

Note however that the 91 or greater octane requirement is for vehicles operating at or near sea level. As the elevation increases, you don't need as much octane, because the higher altitude provides less air, reducing the "effective" compression ratio of the engine. If you live in Denver, they don't even sell 91 octane, because no one needs it.

 

I voted for "what gas do I use?". I have a feeling it will be a landslide.

Better luck with the next poll.

 

I have a '93 z28 and I run regular because i'm extremely tight on money and its my daily driver. The motor is pretty much stock and I have 178,xxx miles on the car. But if I had the money, I would run 91 octane.

 

Funny Funny Funny.. I think,"What gas do I use?" Will be a landslide to. But for real I think I will be going with the 91. It makes sense I will be getting better preformance. Thanks guys..

 

Where are you located?Mohawk& some stations in N.D have their 89/90 octane@ the same price as 87 so there is no reason to run 87 in these cases.Also ,your 93 is far from stock which means that your concerned/value performance,yet try save pennies when filling upBtw @ most gas stations in U.S the premium is 20c/gal. more which ends up average $2.80-$3.00 more!In Canada premium is 10-12c/liter higher which is4.5x higher($5.00 more) so i just don,t get it

 

I also read your sig. & noticed that your have tuning by pcm 4 less.I had tuning by MadZ28 & he offered 2 tunes,one for lower grade& one for premium.I mean why would you pay for a tune but get lower performance.Most of these tuners/chips etc. all recommend prem(91/better) !,again i just don,t see the point in doing your mods,yet saving pennies.

 

O.K. guys I ran out the 87 and put in 89. And I can tell the diff. I will be using med. grade from here on.

 

The different octane fuels provide different properties. In general as octane increases BTU density goes down and burn speed increases. Therefore using a higher octane gas will require more timing advance. Octane rating actually determines the fuel's ability to resist premature detonation. I have a 93 and run premium fuel because I have a 10.8:1 compression ratio, live at sea level and the car was tuned on 93 octane.

 

Generally, octane can not be correlated to burn speed, or energy content

Read section 6.3 of this document carefully:

http://www.faqs.org/faqs/autos/gasoline-faq/part3/

Use of higher octane fuel does not require more advance because it burns slower, it allows more advance due to the absence of end gasses that auto-ignite under higher combustion chamber pressure/temperature.