Regular gas
Safety Car
Joined: Apr 2007
Posts: 4,548
Likes: 609
From: Southeast, WI
Race Director
Joined: Aug 2019
Posts: 12,351
Likes: 14,185
From: Central Illinois
Racer
Joined: Oct 2017
Posts: 445
Likes: 330
From: Katy Texas
Technically there is nothing wrong with putting 87 octane in any modern engine, no matter what the manufacture recommends. They only recommend it so that you get the advertised HP. The computer can sense the fuel type and adjust itself accordingly. It wont hurt the engine. But you will lose 8% to 12% of the advertised HP.
If my vette was a DD, I would strongly consider it since in my area it is almost $1 more a gallon. Luckily I don't DD mine so it only gets the best stuff.
If my vette was a DD, I would strongly consider it since in my area it is almost $1 more a gallon. Luckily I don't DD mine so it only gets the best stuff.
Last edited by xcaliber501; Aug 11, 2019 at 05:17 PM.
3rd Gear
Joined: Aug 2019
Posts: 3
Likes: 1
Well it probably won’t be as bad as when I accidentally put diesel exhaust fluid in my truck’s diesel tank (which is a $2000-$20000 mistake depending on whether you then turn on the ignition). Hmmm, I think I would be inclined to put the recommended fluid in the gas tank.
Race Director
Joined: Aug 2019
Posts: 13,719
Likes: 98
From: 3rd Rock from Sol
Engine mfgs specify a compression ratio, mixture, and many other parameters to offer a significant margin against auto-ignition. The resulting octane rating of that engine insures the detonation and auto-ignition margin are maintained safely. Using a lower octane fuel than the engine designer specifies may result in detonation(notwithstanding the ignition timing) or auto-ignition(dieseling). Both of these are highly detrimental to engine longevity and may severely harm the engine, including potential catastrophic failure(rare).
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Drifting
Joined: Dec 2017
Posts: 1,541
Likes: 729
If you must buy cheapest non “top tier” gas you can find, it might help to carry a pack of the funnel shaped coffee filters in your car. Slip it over the hose nozzle before sticking it in the cars gas receptacle.. then fill very slowly. Caveat: I doubt this would work but its only 2 notches more stupid than deliberately running regular or non “top tier” high test in your Vette IMO.
Team Owner
Joined: Apr 2008
Posts: 31,798
Likes: 2,396
From: Middle TN by way of KY, OH, VA, IL, CA, FL, NY, SC, HI
There are a lot of near-misses in the replies above.
Most every car built after 1998 will run fine on octane as low as 87, if not lower. All cars after that date will detect detonation and "pull timing" to prevent it. What that means is that electronically the ECM is listening full time for detonation and when it detects it, it retards timing until the detonation disappears. The sensors and ECM do this at the speed of billions of a second in real time, updated constantly. As a result your car will run absolutely great on 87 octane 99% of the time and 100% of the time until you romp on it. Then you'll have less power than the car was built to have available - so that available power is wasted. Most of the lost power will be at the top end, under full load, and under full acceleration, or in other words, any time that the full timing advance would be otherwise dialed in.
Most every car built after 1998 will run fine on octane as low as 87, if not lower. All cars after that date will detect detonation and "pull timing" to prevent it. What that means is that electronically the ECM is listening full time for detonation and when it detects it, it retards timing until the detonation disappears. The sensors and ECM do this at the speed of billions of a second in real time, updated constantly. As a result your car will run absolutely great on 87 octane 99% of the time and 100% of the time until you romp on it. Then you'll have less power than the car was built to have available - so that available power is wasted. Most of the lost power will be at the top end, under full load, and under full acceleration, or in other words, any time that the full timing advance would be otherwise dialed in.
Racer
Joined: Jul 2019
Posts: 324
Likes: 313
Nothing adverse -- this is ESPECIALLY TRUE if the C8 has sat ogled, but un-driven, under a car cover in your garage for the last month, and has been waxed at least 4x in the past 4 weeks while it sat idle in your garage. As a super engine protection bonus -- if you wear your New Balance tennies with it when you do take it out and drive it "easy" then for sure you'll be fine. 
Safer yet, buy a Buick or a Caddy, prolly a better fit for ya overall if $3/tank makes any difference for the once a month the car gets out...
Safer yet, buy a Buick or a Caddy, prolly a better fit for ya overall if $3/tank makes any difference for the once a month the car gets out...
Race Director
Joined: Aug 2019
Posts: 13,719
Likes: 98
From: 3rd Rock from Sol
One last time, any engine will auto-ignite/detonate based on int cylinder pressure, temp, mixture, etc. A modern car will detect detonation/pre-ignition by using a frequency sensor based on the piston dia. The point is, a 'detector' means that detonation has already occurred. There is an algorithm that will retard the ignition in an attempt to resolve the detonation. However, detonation has already happened and been detected. Furthermore, the ignition map which has been retarded once, will have a latency recovery algorithm too. This feature tries to advance the timing again, and again, and again(given a delay), to the point where detonation re-starts, then the cycle starts over again.
Sure, you'll get away with running lower octane for a while. The engine almost surely won't grenade when you tromp on it on a hot day, with cheap 87 in the tank. It will just work its way into the detonation margin repeatedly, and pound the top of the bearing journal and other components repeatedly.
I have no skin in the game. It's not my engine. This is the internet - one may think whatever they like.
Sure, you'll get away with running lower octane for a while. The engine almost surely won't grenade when you tromp on it on a hot day, with cheap 87 in the tank. It will just work its way into the detonation margin repeatedly, and pound the top of the bearing journal and other components repeatedly.
I have no skin in the game. It's not my engine. This is the internet - one may think whatever they like.
Last edited by poorwhiteguy; Aug 11, 2019 at 07:49 PM.
Formula 1
Joined: May 2014
Posts: 591
Likes: 236
From: Washington
The ECU will adjust for pinging, but over time there will be carbon buildup that can cause multiple long-range issues. I don't know for sure, but bet you get better fuel mileage with a tier 1 fuel.
Premium is the cleaner and only way to go.
Premium is the cleaner and only way to go.
Melting Slicks
Joined: Jul 2011
Posts: 2,055
Likes: 864
From: So Cal
Basically we put any Top Tier gas in our non-performance cars. But we try and strictly use Chevron or Texaco with Techron in cars like a Corvette or higher HP cars like a CTS V. If we need to occasionally put a Shell or Mobil caliber of gas in those same cars it isn’t a problem. If taking a freeway drive for several hundred or more miles we sometimes use ARCO but just for that trip. No matter what, all of our cars get a bottle of the 20 gallon tank size Techron every six months. Cheap insurance.
Last edited by B747VET; Aug 11, 2019 at 10:55 PM.
Racer
Joined: Oct 2017
Posts: 445
Likes: 330
From: Katy Texas
Here is a clip from the 2019 Corvette owners manual. For the LT1 engine, it clearly states 93 octane fuel is only "recommended" not required. 87 octane fuel is just fine, you just will lose some HP and fuel economy. Even for the supercharged LT4 and LT5 engines, 93 octane is STILL not required, in those engines you can run 91 and do no harm to the engine at all, just with a loss of HP and fuel economy.
The key to look for is to make sure you use a "Top Tier" fuel. Top Tier fuels have nothing to do with the octane rating, it has to do with the quality of the fuel itself. Octane also has nothing to do with the quality of the fuel. All the octane rating tells you is how much pressure the fuel can take before it spontaneously combusts. Nothing else. It is not an indication of carbon content or anything. Simply put, buy your gas from a known brand like Shell or Texaco or Exxon. Don't buy it from Joe Bob's Gas and you'll be fine.
I am not recommending anything. I personally use 93 in my vette. I am just clarifying that it is not required.
Last edited by xcaliber501; Aug 12, 2019 at 09:41 AM.
