octane rating higher than 91 bad too?
10-06-2009, 09:28 AM
#1
octane rating higher than 91 bad too?
Our cars call for 91. I've been using 93 faithfully, and over the past few months I'm one of those guys who's experienced pre-ignition BS. Did some chevron treatments, changed plugs and air filter and it went away 95%. Lately it started coming back a little bit. I filled up with 91 for the first time and its quieted back to 95% gone. Is 93 as bad as 87, since our cars want 91???
10-06-2009, 09:40 AM
#2
I am no expert but I don't think 93 would do any damage because I think it says to use at least 91. I've been running 93 for a while with no problem, actually back when gas was really expensive I was using 89 and the only thing that happened was that my gas mileage went down.
I don't know if this is stupid question but, did you try the fuel filter?
I don't know if this is stupid question but, did you try the fuel filter?
10-06-2009, 09:58 AM
#3
doesnt make much sense..or does it..lol...im interested in some smarter responses..heres my initial response..maybe for some reason the higher octane has a hard time igniting.. which would go along with the theory if you ran race fuel stock..the car would not be able to properly burn it in its stock state...but im not sure if the 2* octane difference is really THAT big of a difference...such as comparing 91/93 vs 104/105
ive always run 93... ill run a tank of 91 for the fun of it next week and see if theres any difference..who knows..
edit:: brand has ALOT to do with it in terms of their detergants and other additives .. example--local no name 93 octane.. vs ..shell 91 octane.... i would take the shell 91...
ive always run 93... ill run a tank of 91 for the fun of it next week and see if theres any difference..who knows..
edit:: brand has ALOT to do with it in terms of their detergants and other additives .. example--local no name 93 octane.. vs ..shell 91 octane.... i would take the shell 91...
Last edited by mist max2000; 10-06-2009 at 10:08 AM.
10-06-2009, 11:15 AM
#4
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Our cars call for 91. I've been using 93 faithfully, and over the past few months I'm one of those guys who's experienced pre-ignition BS. Did some chevron treatments, changed plugs and air filter and it went away 95%. Lately it started coming back a little bit. I filled up with 91 for the first time and its quieted back to 95% gone. Is 93 as bad as 87, since our cars want 91???
There is no difference to your car between using 91 or 93 octane. I believe the maxima uses a 10:1 compression ratio on the air/fuel mix in the cylinder, and this is a higher compression than a lot of cars use. You'll notice that when you buy gas and you see the yellow sticker with the big "93" on it that it does NOT say "93 Octane". Instead, it says "MINIMUM octane rating: 93"
Nissan tells you that you need to use fuel that has a minimum octane rating of 91 because fuel that has a lower octane rating could ignite from heat generated from the high compression before the spark plug fires, hence "pre-ignition". Using fuel with a minimum octane rating of 93 is using fuel that is even further protected from pre-ignition than the 91.
This is why people tell you using premium gas won't give you performance gains.
It is more likely the gas station you were buying 93 from didn't actually have gas with a minimum octane rating of 93 from what you pumped, or you have other mechanical issues with your car causing pre-ignition. I can assure you, however, that using 93 octane instead of 91 will NOT cause your car to knock.
10-06-2009, 12:15 PM
#6
There is no difference to your car between using 91 or 93 octane. I believe the maxima uses a 10:1 compression ratio on the air/fuel mix in the cylinder, and this is a higher compression than a lot of cars use. You'll notice that when you buy gas and you see the yellow sticker with the big "93" on it that it does NOT say "93 Octane". Instead, it says "MINIMUM octane rating: 93"
Nissan tells you that you need to use fuel that has a minimum octane rating of 91 because fuel that has a lower octane rating could ignite from heat generated from the high compression before the spark plug fires, hence "pre-ignition". Using fuel with a minimum octane rating of 93 is using fuel that is even further protected from pre-ignition than the 91.
This is why people tell you using premium gas won't give you performance gains.
It is more likely the gas station you were buying 93 from didn't actually have gas with a minimum octane rating of 93 from what you pumped, or you have other mechanical issues with your car causing pre-ignition. I can assure you, however, that using 93 octane instead of 91 will NOT cause your car to knock.
Nissan tells you that you need to use fuel that has a minimum octane rating of 91 because fuel that has a lower octane rating could ignite from heat generated from the high compression before the spark plug fires, hence "pre-ignition". Using fuel with a minimum octane rating of 93 is using fuel that is even further protected from pre-ignition than the 91.
This is why people tell you using premium gas won't give you performance gains.
It is more likely the gas station you were buying 93 from didn't actually have gas with a minimum octane rating of 93 from what you pumped, or you have other mechanical issues with your car causing pre-ignition. I can assure you, however, that using 93 octane instead of 91 will NOT cause your car to knock.
10-06-2009, 07:29 PM
#8
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10-06-2009, 07:55 PM
#10
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I mean it makes sense right? putting 91 in your honda civic won't do anything right?
10-07-2009, 08:33 AM
#13
Your car will run the same way with 91 or 93 octane fuel. As someone said in an earlier post you have to run at LEAST 91 octane fuel in order to safely operate your car.
That is because fuel with an octane level of less than 91 may prematurely detonate due to the compression and heat within each cylinder of the VQ engine and in turn cause damage to the piston and other components.
93 octane won't make your car run any better or worse. The only reason you may possibly NEED it is if the compression ratio of your engine was increased.
That is because fuel with an octane level of less than 91 may prematurely detonate due to the compression and heat within each cylinder of the VQ engine and in turn cause damage to the piston and other components.
93 octane won't make your car run any better or worse. The only reason you may possibly NEED it is if the compression ratio of your engine was increased.
10-07-2009, 06:20 PM
#14
Hmmm, I was just checking my owner's manual and it says:
FUEL RECOMMENDATION:
Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96)
If unleaded premium gasoline is not available, unleaded regular gasoline with an octane rating of at least 87 AKI (Research octane number 91) can be used.
However,for maximum vehicle performance, the use of unleaded premium gasoline is recommended.
CAUTION:
Using a fuel other than that specified could adversely affect the emission control devices and systems, and could also affect the warranty coverage. Under no circumstances should a leaded gasoline be used, since this will damage the three-way catalyst.
Reformulated gasoline:
Some fuel suppliers are now producing reformulated gasolines. These gasolines are specially designed to reduce vehicle emissions. NISSAN supports efforts towards cleaner air and suggests that you use reformulated gasoline when available.
Gasoline containing oxygenates:
Some fuel suppliers sell gasoline containing oxygenates such as ethanol, MTBE and methanol with or without advertising their presence. NISSAN does not recommend the use of fuels of which the oxygenate content and the fuel compatibility for your NISSAN cannot be readily determined. If in doubt, ask your service station manager.
If you use oxygenate-blend gasoline, please take the following precautions as the usage of such fuels may cause vehicle performance problems and/or fuel system damage.
* The fuel should be unleaded and have an octane rating no lower than that recommended for unleaded gasoline.
* If an oxygenate-blend, excepting a methanol blend, is used, it should contain no more than 10% oxygenate. (MTBE may,however,be added up to 15%.)
* If a methanol blend is used, it should contain no more than 5% methanol(methyl alcohol,wood alcohol). It should also contain a suitable amount of appropriate cosolvents and corrosion inhibitors. If not properly formulated with appropriate cosolvents and corrosion inhibitors, such methanol blends may cause fuel system damage and/or vehicle performance problems. At this time, sufficient data is not available to ensure that all methanol blends are suitable for use in NISSAN vehicles.
If any undesirable driveability problems such as engine stalling and hard hot starting are experienced after using oxygenate-blend fuels, immediately change to a non-oxygenate fuel or a fuel with a low blend of MTBE.
Take care not to spill gasoline during refueling. Gasoline containing oxygenates can cause paint damage.
Aftermarket fuel additives:
NISSAN does not recommend the use of any fuel additives (i.e.fuel injector cleaner,octane booster, intake valve deposit removers, etc.) which are sold commercially. Many of these additives intended for gum, varnish or deposit removal may contain active solvent or similar ingredients that can be harmful to the fuel system and engine.
Guess I've really been screwing up my engine by using 87 octane with 10% ethanol!
FUEL RECOMMENDATION:
Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96)
If unleaded premium gasoline is not available, unleaded regular gasoline with an octane rating of at least 87 AKI (Research octane number 91) can be used.
However,for maximum vehicle performance, the use of unleaded premium gasoline is recommended.
CAUTION:
Using a fuel other than that specified could adversely affect the emission control devices and systems, and could also affect the warranty coverage. Under no circumstances should a leaded gasoline be used, since this will damage the three-way catalyst.
Reformulated gasoline:
Some fuel suppliers are now producing reformulated gasolines. These gasolines are specially designed to reduce vehicle emissions. NISSAN supports efforts towards cleaner air and suggests that you use reformulated gasoline when available.
Gasoline containing oxygenates:
Some fuel suppliers sell gasoline containing oxygenates such as ethanol, MTBE and methanol with or without advertising their presence. NISSAN does not recommend the use of fuels of which the oxygenate content and the fuel compatibility for your NISSAN cannot be readily determined. If in doubt, ask your service station manager.
If you use oxygenate-blend gasoline, please take the following precautions as the usage of such fuels may cause vehicle performance problems and/or fuel system damage.
* The fuel should be unleaded and have an octane rating no lower than that recommended for unleaded gasoline.
* If an oxygenate-blend, excepting a methanol blend, is used, it should contain no more than 10% oxygenate. (MTBE may,however,be added up to 15%.)
* If a methanol blend is used, it should contain no more than 5% methanol(methyl alcohol,wood alcohol). It should also contain a suitable amount of appropriate cosolvents and corrosion inhibitors. If not properly formulated with appropriate cosolvents and corrosion inhibitors, such methanol blends may cause fuel system damage and/or vehicle performance problems. At this time, sufficient data is not available to ensure that all methanol blends are suitable for use in NISSAN vehicles.
If any undesirable driveability problems such as engine stalling and hard hot starting are experienced after using oxygenate-blend fuels, immediately change to a non-oxygenate fuel or a fuel with a low blend of MTBE.
Take care not to spill gasoline during refueling. Gasoline containing oxygenates can cause paint damage.
Aftermarket fuel additives:
NISSAN does not recommend the use of any fuel additives (i.e.fuel injector cleaner,octane booster, intake valve deposit removers, etc.) which are sold commercially. Many of these additives intended for gum, varnish or deposit removal may contain active solvent or similar ingredients that can be harmful to the fuel system and engine.
Guess I've really been screwing up my engine by using 87 octane with 10% ethanol!
10-07-2009, 06:31 PM
#15
10-08-2009, 07:57 AM
#19
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Join Date: Apr 2009
Location: Tucson, AZ
Posts: 388
10-08-2009, 08:29 PM
#20
Minimum of 91 octane. Here in Texas, the choices are 87, 89 and 93, meaning my only real option is 93 octane. And unless the ECU has a restriction of total timing allowed, using 93 octane should allow additional spark timing, making 93 octane no more difficult to ignite than 91 octane and give a small performance gain.
10-08-2009, 08:31 PM
#21
Our cars are old enough that most of us have at least some carbon build-up on the top of the pistons which would slightly raise the compression ratio.
10-08-2009, 09:59 PM
#22
Minimum of 91 octane. Here in Texas, the choices are 87, 89 and 93, meaning my only real option is 93 octane. And unless the ECU has a restriction of total timing allowed, using 93 octane should allow additional spark timing, making 93 octane no more difficult to ignite than 91 octane and give a small performance gain.
Same here. I don't remember ever seeing 91 - only 87, 89, and 93. I think Sunoco also offers 94.
And I can't remember the last time I found a gas station that didn't have a "this contains up to 10% ethanol" sign on the pumps.
10-09-2009, 05:39 AM
#23
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Join Date: Feb 2006
Location: East Granby, Connecticut
Posts: 945
Minimum of 91 octane. Here in Texas, the choices are 87, 89 and 93, meaning my only real option is 93 octane. And unless the ECU has a restriction of total timing allowed, using 93 octane should allow additional spark timing, making 93 octane no more difficult to ignite than 91 octane and give a small performance gain.
The only way you'd see any performance gain from a higher octane is if compression was increased, which I can't really understand how the ECU would automatically adjust the compression for the fuel octane unless it routinely compressed the mixture to pre-ignition to test the octane, which seems VERY unlikely.
I can't see how using higher octane fuel would give performance gain unless you actively tuned the ECU for higher compression.
01-30-2011, 08:16 PM
#24
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Join Date: Sep 2007
Posts: 66
[QUOTE=Rhyno02;7238997]...actually back when gas was really expensive I was using 89 and the only thing that happened was that my gas mileage went down...QUOTE]
Now I wonder if this is why my gas mileage decreased. I thought the check engine light was finally effecting MPGs, but I believe I started using 87/89 when gas hit $4/gallon a couple years ago. I will start using 91 when I get my 5.5 gen next week (hopefully), but will 93 make any difference?
Now I wonder if this is why my gas mileage decreased. I thought the check engine light was finally effecting MPGs, but I believe I started using 87/89 when gas hit $4/gallon a couple years ago. I will start using 91 when I get my 5.5 gen next week (hopefully), but will 93 make any difference?
01-31-2011, 01:48 PM
#26
I've never heard of this before, could you elaborate a bit? I was under the impression the ignition timing wasn't a variable unless pre-ignition occurs, where the timing would be adjusted (at a performance loss) to accommodate lower compression needs.
The only way you'd see any performance gain from a higher octane is if compression was increased, which I can't really understand how the ECU would automatically adjust the compression for the fuel octane unless it routinely compressed the mixture to pre-ignition to test the octane, which seems VERY unlikely.
I can't see how using higher octane fuel would give performance gain unless you actively tuned the ECU for higher compression.
The only way you'd see any performance gain from a higher octane is if compression was increased, which I can't really understand how the ECU would automatically adjust the compression for the fuel octane unless it routinely compressed the mixture to pre-ignition to test the octane, which seems VERY unlikely.
I can't see how using higher octane fuel would give performance gain unless you actively tuned the ECU for higher compression.
Additional spark timing (assuming the ECU allows it) also makes more power by increasing cylinder pressure.
01-31-2011, 01:51 PM
#27
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