Gasoline of choice
04-17-2015, 08:06 AM
#1
Racer
Thread Starter
Gasoline of choice
What grade of fuel do you put into your C4? Also is there a particular brand you like best?
Once I selected regular out of habit as my C4 is not my daily driver and didn't realize it until I put in about a half a tank. I didn't figure it would make that big of a difference but it sure did. The cars performance drop noticeably especially when you got on it. After about a week of driving I went and filled up with premium and it was like driving a different car.
I have read on the internet that some say you're wasting you money buying premium gas but from my experience I am a firm believe that premium gas is the only gas you should use.
Once I selected regular out of habit as my C4 is not my daily driver and didn't realize it until I put in about a half a tank. I didn't figure it would make that big of a difference but it sure did. The cars performance drop noticeably especially when you got on it. After about a week of driving I went and filled up with premium and it was like driving a different car.
I have read on the internet that some say you're wasting you money buying premium gas but from my experience I am a firm believe that premium gas is the only gas you should use.
04-17-2015, 08:27 AM
#2
Safety Car
The grade of gas you use has alot of variables. First is the compression ratio of the engine, condition of the engine and your driving style.
Mine has a 9.5 cr and overall is in decent condition and I use mine as a cruiser so there's no high accelleration runs.
I primarily use 87 octane gas, though I've tried 89 and 91 octane gas. In my case I did not notice any improvement in the engine. My feeling is if it's not pinging or knocking when you're driving then use what your engine runs the best on.
Now as a side note, I've seen engines years back that were carboned up enough to effectively raise the compression ratio of the engine. If yours requires higher octane rated fuel than it should then that's a possibility. If that's the case then may try something like GM Top End Cleaner or Seafoam in a couple of tanks of gas and see if that helps. Also be aware of the fact not all brands of gas will necessarily be the same. There are additives added to the base gas when it's delivered to a station. I've had problems with Marathon branded gas in the past in some of my vehicles, while now I use mostly Shell or Holiday brand gas and have not had issues.
Just thoughts.
Mine has a 9.5 cr and overall is in decent condition and I use mine as a cruiser so there's no high accelleration runs.
I primarily use 87 octane gas, though I've tried 89 and 91 octane gas. In my case I did not notice any improvement in the engine. My feeling is if it's not pinging or knocking when you're driving then use what your engine runs the best on.
Now as a side note, I've seen engines years back that were carboned up enough to effectively raise the compression ratio of the engine. If yours requires higher octane rated fuel than it should then that's a possibility. If that's the case then may try something like GM Top End Cleaner or Seafoam in a couple of tanks of gas and see if that helps. Also be aware of the fact not all brands of gas will necessarily be the same. There are additives added to the base gas when it's delivered to a station. I've had problems with Marathon branded gas in the past in some of my vehicles, while now I use mostly Shell or Holiday brand gas and have not had issues.
Just thoughts.
Last edited by hcbph; 04-17-2015 at 08:30 AM.
04-17-2015, 08:34 AM
#4
Racer
Thread Starter
The grade of gas you use has alot of variables. First is the compression ratio of the engine, condition of the engine and your driving style.
Mine has a 9.5 cr and overall is in decent condition and I use mine as a cruiser so there's no high accelleration runs.
I primarily use 87 octane gas, though I've tried 89 and 91 octane gas. In my case I did not notice any improvement in the engine. My feeling is if it's not pinging or knocking when you're driving then use what your engine runs the best on.
Now as a side note, I've seen engines years back that were carboned up enough to effectively raise the compression ratio of the engine. If yours requires higher octane rated fuel than it should then that's a possibility. If that's the case then may try something like GM Top End Cleaner or Seafoam in a couple of tanks of gas and see if that helps.
Just thoughts.
Mine has a 9.5 cr and overall is in decent condition and I use mine as a cruiser so there's no high accelleration runs.
I primarily use 87 octane gas, though I've tried 89 and 91 octane gas. In my case I did not notice any improvement in the engine. My feeling is if it's not pinging or knocking when you're driving then use what your engine runs the best on.
Now as a side note, I've seen engines years back that were carboned up enough to effectively raise the compression ratio of the engine. If yours requires higher octane rated fuel than it should then that's a possibility. If that's the case then may try something like GM Top End Cleaner or Seafoam in a couple of tanks of gas and see if that helps.
Just thoughts.
04-17-2015, 08:49 AM
#5
Great question, I have a bit to say on this topic.
My boat which has a chevy 454 (merc cruiser) is tuned to run on 87 octane, but myself and everyone else at my marina uses at least 89 and sometimes 91.
Here is why: a boat motor is almost always running under load. I like to think of it as driving up hill all the time. When we use 87 the engine knocks and runs poorly, with the higher octane the boats run much better, and when I take a lot of people out the load is increased even more, I have noticed with 91 she runs awesome under the hardest conditions.
When you stomp on your vette you are putting it under load and similar conditions occur. When I owned my '88 I used 91 and with my '94 I do as well.
As far as brand of gas, my family owned an independent service station throughout the 60's, 70's, and 80's and the brand of gas they got varied weekly with purchase cost. So I am not totally convinced that brand of gas matters because plenty of stations operate this way and multiple brands share the same refineries. HOWEVER, I do believe the condition of the tanks matter! I get my gas at a local Mobil station, not because it is Mobil gas, but the tanks were put in 2 years ago and I feel they are cleaner so the gas going in my vette and silverado is cleaner. Last summer I was running low and could not make it to my Mobil station so I stopped at a Valero station I dont know how old the tanks are, but I know they are not new. My truck ran so crappy on that tank of gas I actually took it in for a diagnosis. Nothing was found to be wrong, 2 tanks of Mobil later and everything was back to normal.
My boat which has a chevy 454 (merc cruiser) is tuned to run on 87 octane, but myself and everyone else at my marina uses at least 89 and sometimes 91.
Here is why: a boat motor is almost always running under load. I like to think of it as driving up hill all the time. When we use 87 the engine knocks and runs poorly, with the higher octane the boats run much better, and when I take a lot of people out the load is increased even more, I have noticed with 91 she runs awesome under the hardest conditions.
When you stomp on your vette you are putting it under load and similar conditions occur. When I owned my '88 I used 91 and with my '94 I do as well.
As far as brand of gas, my family owned an independent service station throughout the 60's, 70's, and 80's and the brand of gas they got varied weekly with purchase cost. So I am not totally convinced that brand of gas matters because plenty of stations operate this way and multiple brands share the same refineries. HOWEVER, I do believe the condition of the tanks matter! I get my gas at a local Mobil station, not because it is Mobil gas, but the tanks were put in 2 years ago and I feel they are cleaner so the gas going in my vette and silverado is cleaner. Last summer I was running low and could not make it to my Mobil station so I stopped at a Valero station I dont know how old the tanks are, but I know they are not new. My truck ran so crappy on that tank of gas I actually took it in for a diagnosis. Nothing was found to be wrong, 2 tanks of Mobil later and everything was back to normal.
04-17-2015, 09:10 AM
#6
Team Owner
The ECM should make some changes when it gets input from the knock sensors. The knock sensors will detect pinging from lower octane gas. As long as you don't drive the car hard, 87 octane should work for in-town daily driver use. I don't think I would use anything other than premium gas if you did a lot of freeway driving, especially if there are hills.
Most states have laws regarding tanks in terms of when they have to be cleaned and when they have to be replaced. And sometimes a carrier will offload a supply of gas and it may have water in it. A station next to our shop got a load of gas last Fall it came out of the pumps looking a dark brown and was nearly opaque. There were something like 15 cars in a day that came into our shop for fuel system cleaning
Most states have laws regarding tanks in terms of when they have to be cleaned and when they have to be replaced. And sometimes a carrier will offload a supply of gas and it may have water in it. A station next to our shop got a load of gas last Fall it came out of the pumps looking a dark brown and was nearly opaque. There were something like 15 cars in a day that came into our shop for fuel system cleaning
04-17-2015, 09:40 AM
#7
Le Mans Master
I run premium.
On my '95 M6, I tried regular on a trip and the mileage dropped about 3 or 4 mpg. It did not return with premium. A couple weeks later I was working on it and disconnected the battery. Next time I drove it the mileage and performance were back.
On my '88 A4, I tried regular and it would ping quite a bit under moderate to heavy load. I returned to premium.
On my '96 Z28 M6, I tried regular and it lost performance. It just did not pull as hard and it took more throttle for normal driving performance. I returned to premium.
On my '94 M6, I tried regular and noticed no difference. I daily drove this 100 miles per day commute and I used regular once in a while.
I am not sure why some cars that should be the same respond differently. For example my '95 M6 is terrible with regular, but my '94 M6 was ok with it. I suspect slight differences in tune and condition of the motor may contribute.
On my '95 M6, I tried regular on a trip and the mileage dropped about 3 or 4 mpg. It did not return with premium. A couple weeks later I was working on it and disconnected the battery. Next time I drove it the mileage and performance were back.
On my '88 A4, I tried regular and it would ping quite a bit under moderate to heavy load. I returned to premium.
On my '96 Z28 M6, I tried regular and it lost performance. It just did not pull as hard and it took more throttle for normal driving performance. I returned to premium.
On my '94 M6, I tried regular and noticed no difference. I daily drove this 100 miles per day commute and I used regular once in a while.
I am not sure why some cars that should be the same respond differently. For example my '95 M6 is terrible with regular, but my '94 M6 was ok with it. I suspect slight differences in tune and condition of the motor may contribute.
04-17-2015, 09:53 AM
#8
Safety Car
There are no brands in San Diego Co. There is one pipeline from Los Angeles to 1 truck terminal in town. Each gas station blends it's own additive during the tanker truck fill. Even then I think it is the same additive, just different quantities.
So we get the same ethanol gas at every station. Only Costco blends its own additive at the gas station itself...look around and you will see an outdoor cabinet and storage tank for their additives.
So we get the same ethanol gas at every station. Only Costco blends its own additive at the gas station itself...look around and you will see an outdoor cabinet and storage tank for their additives.
04-17-2015, 10:11 AM
#9
Racer
Thread Starter
04-17-2015, 12:36 PM
#11
Burning Brakes
I really never noticed a performance issue with mine but I've never used 87 octane in it. I have mixed 89 and 91 together a couple of times but my 90 L98 gets the best gas mileage using 91.
As for brand I seldom use anything other than Chevron. No particular reason other than I've never had a fuel system problem using it for over 30 years. I've heard that the Techron additive is particularly good for C4/C5 Corvettes. Something about it preventing corrosion on the float in the tank or something like that.
As for brand I seldom use anything other than Chevron. No particular reason other than I've never had a fuel system problem using it for over 30 years. I've heard that the Techron additive is particularly good for C4/C5 Corvettes. Something about it preventing corrosion on the float in the tank or something like that.
04-17-2015, 02:50 PM
#14
Melting Slicks
93 Octane Shell, Exxon, BP, or Chevron. I also keep Sta-Bil in the tank all of the time. In Germany I ran 97.
Last edited by HGUNHNTR; 04-17-2015 at 02:52 PM.
04-17-2015, 04:18 PM
#16
Racer
Thread Starter
That is the same I believe in Pennsylvania. I don't think there is any place that has E-Zero. None that I've seen in Western PA.
04-17-2015, 04:19 PM
#17
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04-17-2015, 04:35 PM
#18
Pro
04-17-2015, 06:02 PM
#19
Drifting
04-17-2015, 07:14 PM
#20
Le Mans Master
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Better performance on premium gas? Yes...C4s included, beginning with the application of computer controlled fueling and timing. But! it wasn't always that way! A lot of water went over the dam between the into to NO-LEAD gasoline and the wait for computer technology to catch up and save the day for performance enthusiasts!
Up until the beginning of the 80s, Corvette engines were carbureted. Fueling and timing were manually adjusted according to a specific type of operating parameters. After computers with the real-time input from the O2 and knock sensors were developed and improved, the motors could be optimized to run on high octane fuels, but could detect knock if lower octane, i.e., 87 octane was being used. (Federal EPA has required all manufactures make engines capable of operating on 87 octane - which has been in effect for over 3 decades, IIRC.)
So, for those that experience better performance and perhaps fuel economy when burning higher octane...thank your computer and it sensors. If doing a long haul cross-country run, could you maybe do with 87 octane? Check your owners manual, but chances are you will get along just fine - long as you keep your danged food off the "GO" peddle!
Up until the beginning of the 80s, Corvette engines were carbureted. Fueling and timing were manually adjusted according to a specific type of operating parameters. After computers with the real-time input from the O2 and knock sensors were developed and improved, the motors could be optimized to run on high octane fuels, but could detect knock if lower octane, i.e., 87 octane was being used. (Federal EPA has required all manufactures make engines capable of operating on 87 octane - which has been in effect for over 3 decades, IIRC.)
So, for those that experience better performance and perhaps fuel economy when burning higher octane...thank your computer and it sensors. If doing a long haul cross-country run, could you maybe do with 87 octane? Check your owners manual, but chances are you will get along just fine - long as you keep your danged food off the "GO" peddle!
Last edited by Paul Workman; 04-17-2015 at 07:21 PM.