Fill up 93 or 94 octane for 02TL?
04-22-2002 | 07:57 AM
#2
Three Wheelin'
Joined: May 2000
Posts: 1,776
Likes: 1
From: Washington DC.
Fill up on 91 octane or higher that is what it says in the owners manual. I use 93 octane because thats what most of the stations sell here as premium. We can get 94 octane from Sunoco stations here. The Sunoco cost more here so why get it when you don't need it. If say the station you buy gas from all the time only sells 94 octane as its premium fuel then get it.
04-22-2002 | 01:51 PM
#6
Cruisin'
Joined: Feb 2002
Posts: 15
Likes: 0
What does octane rating mean?
Buying higher octane than necessary is a waste of your money. To understand why, you need to first understand what the octane rating means.
Octane is a hydrocarbon. A hydrocarbon is a bunch of carbon atoms bonded together in a chain with hyrdrogen atoms bonded to those carbon atoms. The reason we call it octane is because there are eight carbon atoms in the chain (Greek prefix "oct-", like an octagon). When an unstable hydrocarbon like octane or butane is exposed to energy (such as a spark) in the presence of oxygen, then the chemical bonds between the carbon and hydrogen atoms all start breaking down in a chain reaction, and that is how we get combustion of gasoline.
The "octane" rating is actually a ratio. There are two chemical compounds from which the octane rating is derived. They are isooctane and isobutane. Isooctane is relatively well behaved and stable when compared to isobutane, and requires much more energy than isobutane to start the combustion chain reaction.
One of the important factors when dealing with combustion engines is what happens to the gasoline when a spark is not present. The gasoline is in a very hot engine cylinder under high compression, and may spontaneously combust from the heat energy and pressure alone. Isobutane is very prone to this phenomenon where it combusts in the absence of a spark, where as isooctane is more resistant to this. When there is combustion in an engine cylinder without a spark (ie, before the spark plug fires), then the fuel will combust when it is not supposed to and the firing order of the cylinders is thrown off. It will make a rather unpleasant sound of a small explosion going off under your hood. This is called engine knock.
The octane rating on a gasoline is a way to compare how resistant a gasoline is against this untimely spontaneous combustion. A gasoline that is 93 octane behaves the same was as a mixture of 93% isooctane and 7% isobutane. Thus, an 87 octane gasoline will spontaneously combust under heat and pressure more frequently than a 93 octane gasoline. It is possible to find gasolines and compounds that are over 100 octane and behave more ideally against engine knock than pure octane. Methanol gasolines used in race car engines fall into this 100+ octane category.
When a car is rated at 91 octane, the engineers have determined that 91 octane is required to prevent engine knock. They examine factors such as compression ratio, air intake, temperature of an engine cylinder, just to name a few. And because they recommend 91, they have made adjustments to the fuel pump and air intake system to operate most efficiently when using 91 octane.
So what happens when you put 93 or 94 octane in a car rated at 91 octane? Not much more than if you just had 91 octane. You don't have engine knock at 91 octane anyway, so going up to 93 or 94 won't make a difference. The amount of air you intake and the compression ratio aren't properly calibrated to make use of the marginal energy boost from 91 to 94, so you won't notice a difference.
Therefore, your car will not perform noticeably better or worse on 91, 93, or 94 octane. It is best just to buy the gas closest to the recommended octane rating.
Octane is a hydrocarbon. A hydrocarbon is a bunch of carbon atoms bonded together in a chain with hyrdrogen atoms bonded to those carbon atoms. The reason we call it octane is because there are eight carbon atoms in the chain (Greek prefix "oct-", like an octagon). When an unstable hydrocarbon like octane or butane is exposed to energy (such as a spark) in the presence of oxygen, then the chemical bonds between the carbon and hydrogen atoms all start breaking down in a chain reaction, and that is how we get combustion of gasoline.
The "octane" rating is actually a ratio. There are two chemical compounds from which the octane rating is derived. They are isooctane and isobutane. Isooctane is relatively well behaved and stable when compared to isobutane, and requires much more energy than isobutane to start the combustion chain reaction.
One of the important factors when dealing with combustion engines is what happens to the gasoline when a spark is not present. The gasoline is in a very hot engine cylinder under high compression, and may spontaneously combust from the heat energy and pressure alone. Isobutane is very prone to this phenomenon where it combusts in the absence of a spark, where as isooctane is more resistant to this. When there is combustion in an engine cylinder without a spark (ie, before the spark plug fires), then the fuel will combust when it is not supposed to and the firing order of the cylinders is thrown off. It will make a rather unpleasant sound of a small explosion going off under your hood. This is called engine knock.
The octane rating on a gasoline is a way to compare how resistant a gasoline is against this untimely spontaneous combustion. A gasoline that is 93 octane behaves the same was as a mixture of 93% isooctane and 7% isobutane. Thus, an 87 octane gasoline will spontaneously combust under heat and pressure more frequently than a 93 octane gasoline. It is possible to find gasolines and compounds that are over 100 octane and behave more ideally against engine knock than pure octane. Methanol gasolines used in race car engines fall into this 100+ octane category.
When a car is rated at 91 octane, the engineers have determined that 91 octane is required to prevent engine knock. They examine factors such as compression ratio, air intake, temperature of an engine cylinder, just to name a few. And because they recommend 91, they have made adjustments to the fuel pump and air intake system to operate most efficiently when using 91 octane.
So what happens when you put 93 or 94 octane in a car rated at 91 octane? Not much more than if you just had 91 octane. You don't have engine knock at 91 octane anyway, so going up to 93 or 94 won't make a difference. The amount of air you intake and the compression ratio aren't properly calibrated to make use of the marginal energy boost from 91 to 94, so you won't notice a difference.
Therefore, your car will not perform noticeably better or worse on 91, 93, or 94 octane. It is best just to buy the gas closest to the recommended octane rating.
04-22-2002 | 03:01 PM
#7
Instructor
Joined: Aug 2001
Posts: 179
Likes: 0
From: Fort Worth, TX
Fill up with anything 91+ and you’ll be fine.
Higher Octane is better gas, even if your car dosen't respond to it. Higher Octane is cleaner and better.
I recommend getting the premium at any gas station instead of "middle grades"
Higher Octane is better gas, even if your car dosen't respond to it. Higher Octane is cleaner and better.
I recommend getting the premium at any gas station instead of "middle grades"
Trending Topics
04-22-2002 | 04:13 PM
#8
Banned
Joined: Jul 2001
Posts: 1,687
Likes: 3
From: Mundelein, IL
Re: What does octane rating mean?
Originally posted by kent1146
Buying higher octane than necessary is a waste of your money. To understand why, you need to first understand what the octane rating means.
Octane is a hydrocarbon. A hydrocarbon is a bunch of carbon atoms bonded together in a chain with hyrdrogen atoms bonded to those carbon atoms. The reason we call it octane is because there are eight carbon atoms in the chain (Greek prefix "oct-", like an octagon). When an unstable hydrocarbon like octane or butane is exposed to energy (such as a spark) in the presence of oxygen, then the chemical bonds between the carbon and hydrogen atoms all start breaking down in a chain reaction, and that is how we get combustion of gasoline.
The "octane" rating is actually a ratio. There are two chemical compounds from which the octane rating is derived. They are isooctane and isobutane. Isooctane is relatively well behaved and stable when compared to isobutane, and requires much more energy than isobutane to start the combustion chain reaction.
One of the important factors when dealing with combustion engines is what happens to the gasoline when a spark is not present. The gasoline is in a very hot engine cylinder under high compression, and may spontaneously combust from the heat energy and pressure alone. Isobutane is very prone to this phenomenon where it combusts in the absence of a spark, where as isooctane is more resistant to this. When there is combustion in an engine cylinder without a spark (ie, before the spark plug fires), then the fuel will combust when it is not supposed to and the firing order of the cylinders is thrown off. It will make a rather unpleasant sound of a small explosion going off under your hood. This is called engine knock.
The octane rating on a gasoline is a way to compare how resistant a gasoline is against this untimely spontaneous combustion. A gasoline that is 93 octane behaves the same was as a mixture of 93% isooctane and 7% isobutane. Thus, an 87 octane gasoline will spontaneously combust under heat and pressure more frequently than a 93 octane gasoline. It is possible to find gasolines and compounds that are over 100 octane and behave more ideally against engine knock than pure octane. Methanol gasolines used in race car engines fall into this 100+ octane category.
When a car is rated at 91 octane, the engineers have determined that 91 octane is required to prevent engine knock. They examine factors such as compression ratio, air intake, temperature of an engine cylinder, just to name a few. And because they recommend 91, they have made adjustments to the fuel pump and air intake system to operate most efficiently when using 91 octane.
So what happens when you put 93 or 94 octane in a car rated at 91 octane? Not much more than if you just had 91 octane. You don't have engine knock at 91 octane anyway, so going up to 93 or 94 won't make a difference. The amount of air you intake and the compression ratio aren't properly calibrated to make use of the marginal energy boost from 91 to 94, so you won't notice a difference.
Therefore, your car will not perform noticeably better or worse on 91, 93, or 94 octane. It is best just to buy the gas closest to the recommended octane rating.
Buying higher octane than necessary is a waste of your money. To understand why, you need to first understand what the octane rating means.
Octane is a hydrocarbon. A hydrocarbon is a bunch of carbon atoms bonded together in a chain with hyrdrogen atoms bonded to those carbon atoms. The reason we call it octane is because there are eight carbon atoms in the chain (Greek prefix "oct-", like an octagon). When an unstable hydrocarbon like octane or butane is exposed to energy (such as a spark) in the presence of oxygen, then the chemical bonds between the carbon and hydrogen atoms all start breaking down in a chain reaction, and that is how we get combustion of gasoline.
The "octane" rating is actually a ratio. There are two chemical compounds from which the octane rating is derived. They are isooctane and isobutane. Isooctane is relatively well behaved and stable when compared to isobutane, and requires much more energy than isobutane to start the combustion chain reaction.
One of the important factors when dealing with combustion engines is what happens to the gasoline when a spark is not present. The gasoline is in a very hot engine cylinder under high compression, and may spontaneously combust from the heat energy and pressure alone. Isobutane is very prone to this phenomenon where it combusts in the absence of a spark, where as isooctane is more resistant to this. When there is combustion in an engine cylinder without a spark (ie, before the spark plug fires), then the fuel will combust when it is not supposed to and the firing order of the cylinders is thrown off. It will make a rather unpleasant sound of a small explosion going off under your hood. This is called engine knock.
The octane rating on a gasoline is a way to compare how resistant a gasoline is against this untimely spontaneous combustion. A gasoline that is 93 octane behaves the same was as a mixture of 93% isooctane and 7% isobutane. Thus, an 87 octane gasoline will spontaneously combust under heat and pressure more frequently than a 93 octane gasoline. It is possible to find gasolines and compounds that are over 100 octane and behave more ideally against engine knock than pure octane. Methanol gasolines used in race car engines fall into this 100+ octane category.
When a car is rated at 91 octane, the engineers have determined that 91 octane is required to prevent engine knock. They examine factors such as compression ratio, air intake, temperature of an engine cylinder, just to name a few. And because they recommend 91, they have made adjustments to the fuel pump and air intake system to operate most efficiently when using 91 octane.
So what happens when you put 93 or 94 octane in a car rated at 91 octane? Not much more than if you just had 91 octane. You don't have engine knock at 91 octane anyway, so going up to 93 or 94 won't make a difference. The amount of air you intake and the compression ratio aren't properly calibrated to make use of the marginal energy boost from 91 to 94, so you won't notice a difference.
Therefore, your car will not perform noticeably better or worse on 91, 93, or 94 octane. It is best just to buy the gas closest to the recommended octane rating.
04-22-2002 | 04:35 PM
#9
10th Gear
Joined: Apr 2002
Posts: 11
Likes: 0
Is it necessarily bad if I put the "middle grade" gas into my car (89 octane)? If the octane rating is the susceptibility of the gas to ignite accidentally, will a 2% difference between 91 and 89 make that big a difference? Am I going to lose power, or am I simply running the risk of getting engine knock every once in a while? Aren't engines designed to retime themselves if a repetitive engine knock is detected?
04-22-2002 | 04:58 PM
#10
Banned
Joined: Jul 2001
Posts: 1,687
Likes: 3
From: Mundelein, IL
Originally posted by Rayster
Is it necessarily bad if I put the "middle grade" gas into my car (89 octane)? If the octane rating is the susceptibility of the gas to ignite accidentally, will a 2% difference between 91 and 89 make that big a difference? Am I going to lose power, or am I simply running the risk of getting engine knock every once in a while? Aren't engines designed to retime themselves if a repetitive engine knock is detected?
Is it necessarily bad if I put the "middle grade" gas into my car (89 octane)? If the octane rating is the susceptibility of the gas to ignite accidentally, will a 2% difference between 91 and 89 make that big a difference? Am I going to lose power, or am I simply running the risk of getting engine knock every once in a while? Aren't engines designed to retime themselves if a repetitive engine knock is detected?
The question I ask to all those who don't want to shell out the extra $100 - $200 a year for premium vs. regular (depending on driving on mileage of course).
If you're getting lower gas mileage by putting regular or mid-grade in your car, what's the point? The money your saving is offset by the fact that you will have to fill up sooner.
04-22-2002 | 07:50 PM
#12
Burning Brakes
Joined: May 2001
Posts: 883
Likes: 1
From: Southern Cali - Riverside Area
Re: What does octane rating mean?
Originally posted by kent1146
Buying higher octane than necessary is a waste of your money. To understand why, you need to first understand what the octane rating means.
Octane is a hydrocarbon. ...
Buying higher octane than necessary is a waste of your money. To understand why, you need to first understand what the octane rating means.
Octane is a hydrocarbon. ...
Wow! Excellent explanation! Even I understand now!
V.
P.S. And now I'm no longer jealous of those guys who can get 92+ octane for their cars (Northern Cali only sells 91 octane).
04-23-2002 | 06:13 AM
#13
Burning Brakes
Joined: Mar 2002
Posts: 1,146
Likes: 0
Originally posted by kent1146
The reason we call it octane is because there are eight carbon atoms in the chain (Greek prefix "oct-", like an octagon).
The reason we call it octane is because there are eight carbon atoms in the chain (Greek prefix "oct-", like an octagon).
Great explanation kent1146
11-27-2002 | 10:24 AM
#18
Three Wheelin'
Joined: Oct 2001
Posts: 1,506
Likes: 0
From: Louisville
Originally posted by Strannik
Usually when temperature falls, the engine is less likely to knock on gas with lesser octane rating. So I am using 93 in summer, but once it gets below 50F, it runs just fine on 89.
Usually when temperature falls, the engine is less likely to knock on gas with lesser octane rating. So I am using 93 in summer, but once it gets below 50F, it runs just fine on 89.
11-27-2002 | 11:15 AM
#19
On the way!
Joined: Oct 2001
Posts: 3,715
Likes: 0
From: Orlando, FL
Originally posted by Dimsumo
Higher Octane is better gas, even if your car dosen't respond to it. Higher Octane is cleaner and better.
Higher Octane is better gas, even if your car dosen't respond to it. Higher Octane is cleaner and better.
"As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car’s engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car."
12-13-2002 | 03:49 PM
#21
Cruisin'
Joined: May 2002
Posts: 15
Likes: 0
From: Shrewsbury, MA
here is a link showing two dynos of a car (VW VR6) designed for 91+ octane . one dyno on 89, one on premium...its pretty self-explanatory. 
http://dynospotracing.com/octane.htm
http://dynospotracing.com/octane.htm
Thread
Thread Starter
Forum
Replies
Last Post
rp_guy
Member Cars for Sale
9
07-16-2017 07:33 AM
