On the highway you'll see a few MPG less.

 

Not quite correct. Quoting the apparent higher octane of ethanol misses an important point. Ethanol makes less power than gasoline.
Ethanol at 10% of the total mix, will cause you to lose 2-3% of the horsepower the engine could provide on pure gasoline, with an attendant loss in fuel economy as well.

 

Based on your post's criteria, I would say you lost the bet..... On both counts.

Using lower octane fuel in a high compression engine cause both a loss of performance AND it damages the engine, from pre-detonation knock. As said in the owner's manual, even fuel that is rated at 87 octane will produce knock and if the engine is knocking, you're causing damage.... Sounds to me like you lost.

 

Actually, you are wrong. 87 octane MAY produce knock (the words MAY and MIGHT are in the owner's manual - not WILL) - it's not an absolute that it WILL produce knock. There is a difference. It's all in how hard you push the throttle. If you drive the car in a sedate fashion (and I'll bet there are many that do commonly; I'll admit to it) it won't knock and therefore no damage is done. This entire post is about a theoretical situation for the purpose of winning a bet. With this said I'll add that I always use premium fuel in my Vette.

Many of us have experience with this from our youth - I routinely advanced the timing on my high school car beyond what was recommended because it ran better. IF I jumped on it hard it would ping / knock unless I was burning premium fuel. In "general" driving I got away with it with regular fuel. I never burned a hole in a piston - but some of my friends did.

 

Just show him JimTN's page from the owner's manual and you win the bet.

 

Based on this theory, I MAY/MIGHT get a ticket driving 130mph on the highway. My theory is that I WILL get a ticket the longer I do it. Using a lower octane fuel in the C6 MAY/MIGHT cause damage in the short term but eventually WILL cause damage if you continue to use it. The OP never said anything about running lower octane at idle or gently-what's the point of that? That's just my opinion. //art

 

I'm also one of those who burned a hole in the top of my piston (not the vette) by advancing the timing so the engine ran better.

 

But you will experience power loss on accel if pinging is detected. And pinging (which is pre-detonation, or 2 flame fronts colliding from improper fuel burning) , will damage your engine.

OK. Still doesn't state why anyone would use 87 octane.

 

Ethanol mix aside, a higher octane fuel burns SLOWER than a lower octane fuel which has the effect of a "cleaner" burning of residual gases and deposits which WILL form on pistons and valves if a lower octane fuel is used. These undesirable deposits WILL be detrimental to the overall operating efficiency of an internal combustion engine. It's ALWAYS better to use a higher octane fuel regardless of usage.

Additionally, don't think that all fuels of the same octane rating are the same--they're not. Some refiners produce better fuels because of the composition of the additives contained therein. It's not necessary to get into a preference debate, but the cheap off-the-wall brands of gasoline are NOT of the same quality as certain other more widely known gasolines, i.e. Shell, Chevron, Phillips, Conoco, et.al.

 

the 'no damage' dude wins the bet. here's why.
owners manual clearly indicates that 87 octane is SUPPORTED.
(it can be either supported or not supported ; it either violates warranty or does not. warranty is not violated, so 87 octane is therefore supported.)

also there seems to be a misconception among some folks that knocking is the same as pinging. it's not.
i understand that best mpg is achieved with a tiny bit of ping that only dogs and knock-sensors can hear! the ECM is adjusting timing to achieve an optimal level of ping, not to eliminate all ping.

additionally i have run the best controlled tests i can with 87 vs 91 and with nonethanol-vs-ethanolgas and mtbe-vs-ethanol oxygenate tests. for 87 vs 91 and a raft of Z28s & a GTO I have demonstrated better mpg with 87 repeatably, with highway driving. with city driving it seems that 87 octane drops my mpg by no more than 5%, making it a lower $/mile for all driving types when the 92 octane fuel is priced absurdly higher than the 87, which is true at some gas stations.

I find the lower power/torque with 87 only to be noticeable when temps are ~40F so in winter/cold-weather I tend to run 87 for months at a time. I drive my 05 gto plenty in winter during the dry/cold no-snow spells.

also I am a Corvette wannabee, just so you know why i'm here .
i'm thinking base-model some year soon - with stickshift and magna-ride as the only options. local chevy dealer is 'very aggressive' on vette pricing. :}

 

Patently not true. YLOFEVR will not be able to produce any reputable fuel industry or automotive report that supports the gases/deposits claim for lower octane fuels in modern engines. These days, all of the gasoline from the major gas companies contain more than enough detergents to keep your engine clean. Period.


The name on the service station sign does not tell the whole story. The fact that you purchase gasoline from a given company does not necessarily mean that the gasoline was actually produced by that particular company's refineries. While gasoline is sold at about 162,000 retail outlets across the nation, about one-third of these stations are “unbranded” dealers that may sell gasoline of any brand. The remainder of the outlets are “branded” stations, but may not necessarily be selling gasoline produced at that company's refineries. This is because gasoline from different refineries is often combined for shipment by pipeline, and companies owning service stations in the same area may be purchasing gasoline at the same bulk terminal. In that case, the only difference between the gasoline at station X versus the gasoline at station Y may be the small amount of additives that those companies add to the gasoline before it gets to the pump.

Even if we knew at which company's refinery the gasoline was produced, the source of the crude oil used at that refinery may vary on a day-to-day basis. Most refiners use a mix of crude oils from various domestic and foreign sources. The mix of crude oils can change based on the relative cost and availability of crude oil from different sources.

Source:
U.S. Dept. of Energy.

 

Why is this so complicated? The OP simply asked if you CAN run 87 octane without damaging anything. The answer is yes you can if you are just going to be putting around town. Don't expect to get any kind of performance out of your engine without damaging it. But if you are just cruising you can get away with it.

 

You should be ok as long as the knock sensor operates properly, so under normal conditions with everything operating as it should there should be no damage. But I would not use 87 unless you had no other choice, it's not the recommended fuel.

As you can see this always stirs up controversy.