Stupid Question

[captras]

Had a disagreement with a buddy....says that you can run a C5 on Mid Grade fuel as long as you dont dog it! I was of the assumption the 93 octane is minimum, and anything else would damage the engine. Any answers?

Thanks

 

[KOPBET]

If that were the case then there would be a LOT of dead Corvettes around here. 93 octane is not easy to find, especially at top tier gasoline retailers.

 

[captras]

If that were the case then there would be a LOT of dead Corvettes around here. 93 octane is not easy to find, especially at top tier gasoline retailers.

Actually, I misspoke...I meant premium grade fuel, not necessarily 93 octane, as compared to the mid grade fuels (89 Oct)

 

[gmjunkie]

Actually, I misspoke...I meant premium grade fuel, not necessarily 93 octane, as compared to the mid grade fuels (89 Oct)

Well my owners Manual says 87 Octane or Above!! It's all considered Premium fuel here in the US just some of it is more Premium than others!!

PS My C5 runs better and gets 30++ MPG on Chevron Regular,better than it does Premium or Mid-grade!! But I won't put any Ethanol Gas in it!!!!

 

[KOPBET]

Quote from LS1 manual.

"Use premium unleaded gaoliine of 91 or higher octane rating for best performance. You may use middle grade or regular unleaded gasolines, but your vehicle may not accelerate as well"

 

[gmjunkie]

Quote from LS1 manual.

"Use premium unleaded gaoliine of 91 or higher octane rating for best performance. You may use middle grade or regular unleaded gasolines, but your vehicle may not accelerate as well"

I don't have any problem Accelerating Kop!!!When you nail it and the Road starts Yelling at the tires,it's Accelerating Fast Enough!!!

 

[KOPBET]

I don't have any problem Accelerating Kop!!!

You guys in NC cheat!! You can add shine to your tank!!!!

 

[jrose7004]

All we can get around here is 91.

 

[bwing]

My neighbor had been using regular gas for a little more than a year in his '02 C5 and he said it fouled up his injectors. I'm afraid to use anything less than premium in mine for fear of damage that would void the warranty. Every other month I pour in a bottle of Chevron injector cleaner with a tank of gas.

 

[napacruzerC5]

All we can get around here is 91.

Same here in the great Republik of Kalifornia. For an average price of 20-cents more per gallon a typical 15 gallon fill up would cost $3 more. How much do you drive your vette? Maybe as a daily driver racking up lots of miles the extra $3 per fillup may drive you broke. For my weekender - with maybe one fillup per month it doesn't make any sense.

 

[vett boy]

I use 89 or mid grade. As others note GM says you can use almost anything you want to.

 

[roxeye1]

My C5 2K manual recommeneds premium (91) ONLY! Thought I'd try n' pinch a penny and use mid-grade - My motor started knocking and sounded really bad!! Not worth the savings - Went back to premium, knock went away - MY QUESTION IS, technically, how is the lower grade fuel producing such an awful sound? Car's to nice to be cheap!

 

[Chemdawg99]

My C5 2K manual recommeneds premium (91) ONLY! Thought I'd try n' pinch a penny and use mid-grade - My motor started knocking and sounded really bad!! Not worth the savings - Went back to premium, knock went away - MY QUESTION IS, technically, how is the lower grade fuel producing such an awful sound? Car's to nice to be cheap!

The reason for using 91 or higher octane fuel is the high compression of the Gen III V-8 engine.

Higher compression ratios produce more power, up to a point. The more you compress the air/fuel mixture, however, the more likely it is to spontaneously burst into flame (before the spark plug ignites it.You know, pinging, knocking). Higher-octane gasolines prevent this sort of early combustion. That is why high-performance cars like ours generally need high-octane gasoline. Their engines are using higher compression ratios to get more power. Hope this explaination helps.

 

[Mike Mercury]

My neighbor had been using regular gas for a little more than a year in his '02 C5 and he said it fouled up his injectors.

Since when does "octane" have any effect on injectors ??? Cheap gas may have this bad effect; but then cheap "93" octane gas would also.

I'm afraid to use anything less than premium in mine for fear of damage that would void the warranty.

where in the warranty does it state anything about the octane rating of the fuel ? Someone already had quoted directly friom the owners manual... stating that even 87 octane could be used...

I pour in a bottle of Chevron injector cleaner with a tank of gas.

not a bad idea at all.

 

[gmjunkie]

Heres my average Last 2800+ mile trip!!

The car has had Regular Chevron used in it since new,or if I can't get Chevron where I'm at a bottle of Tectron with each fill up!!

 

[Hib Halverson]

Had a disagreement with a buddy....says that you can run a C5 on Mid Grade fuel as long as you dont dog it! I was of the assumption the 93 octane is minimum, and anything else would damage the engine. Any answers?

Thanks

You're buddy is right...well, kinda sorta.

Depending on model year, GM recommends either 91 or 93 octane but the engine will run safely on a minimum of 87-oct at low altitude and a min. of 85-oct in high altitude areas. And....you need not worry about "dogging" it.

What saves your butt is feedback control of spark advance through detonation (knock) sensing and computer control of the spark.

If you run less than 91/93, the engine may not perform as well and may run a little warmer (due to retarded spark under load) but you won't hurt it.

 

[minifridge1138]

Low octane won't clog the injectors.

All a low octane will do is give you some spark knock.
You should use the lowest octane that does not cause pre-detonation. Any higher octane is just a waste of money.

If something clogged his injectors, then he got dirty fuel and that can happen at any octane.

 

[roxeye1]

2K manual, page 6-3: "Use premium unleaded gasoline rated at 91 octane or higher for best performance. You may use middle grade or regular unleaded gasolines, but your vehicle's acceleration may be slightly reduced." Thanks for the input, but after hearing what less than 91 octane sounds like, the choice for me becomes a no-brainer!

 

[killain]

You're buddy is right...well, kinda sorta.

Depending on model year, GM recommends either 91 or 93 octane but the engine will run safely on a minimum of 87-oct at low altitude and a min. of 85-oct in high altitude areas. And....you need not worry about "dogging" it.

What saves your butt is feedback control of spark advance through detonation (knock) sensing and computer control of the spark.

If you run less than 91/93, the engine may not perform as well and may run a little warmer (due to retarded spark under load) but you won't hurt it.

Huh, Great info Mr. Halverson. I never realized that the retarded spark would raise the operating temps. I've read many,many of your articles and columns and can trust anything you quote. Plus, I don't think there is anything like a 'Stupid' question. That's why there's fourms like this one, for questions. Here we learn things we didn't know before.

ps, I loved the story about when you bought your ZR-1, Very captivating reading.

 

[ScottNoxid]

The car has had Regular Chevron used in it since new,or if I can't get Chevron where I'm at a bottle of Tectron with each fill up!!

Hey Junkie, was your trip going downhill? There is something amiss here. My last trip of about 2400 miles I avg around 24mpg, and I cruise right at 80 in 6th gear. My rpm's are right where yours show. I use nothing but premium gas. Now this included 4 times on the Dragon, and a lot of mountain travel on the interstate, but you are showing 10 more miles to the gallon. What gives?