Do you stop using premium fuel at $4 gallon? $5?
#101
Join Date: Oct 2009
Location: Perth Ontario Canada
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I do not totally disagree with your generalizations of detonation and pre-ignition but it must be understood that each normally exists independently of the other and without any inherent connection. One frequently exists without the other, in other words. No one here is advocating operating an engine with any measure of detonation for even a brief period even if they 'could get away with it'.
Yes, varying opinions are what make civil discussions enjoyable.
#102
Like JimC64 said on page #1.
We are sitting at $1.68/litre here, and have been for a looooong time.
ALL my/our Jags get our 98 Premium, no exceptions.
A blown piston, overheated engine, whatever, is just not worth the brain cells to consider the lesser fuel.
Then consider the "drinking time" you are going to miss out on whilst you repair that engine, NAH, too stressful.
We are sitting at $1.68/litre here, and have been for a looooong time.
ALL my/our Jags get our 98 Premium, no exceptions.
A blown piston, overheated engine, whatever, is just not worth the brain cells to consider the lesser fuel.
Then consider the "drinking time" you are going to miss out on whilst you repair that engine, NAH, too stressful.
#103
Spinall-
There's a simple reason why octane ratings of gas sold at high altitude are lower than at sea level. The air is thinner resulting in peak cylinder pressures. This means that the potential for detonation is reduced as is the requirement for octane enhancing additives.
Keep in mind that octane levels have nothing to do with gasoline 'quality', 'purity' or levels of other additives.
There's a simple reason why octane ratings of gas sold at high altitude are lower than at sea level. The air is thinner resulting in peak cylinder pressures. This means that the potential for detonation is reduced as is the requirement for octane enhancing additives.
Keep in mind that octane levels have nothing to do with gasoline 'quality', 'purity' or levels of other additives.
Even children in school here know that they sell lower octane gas beacuse of the elevation, and how it makes normal cars detonate less.
I'm not quite sure why you were trying to make your self feel smarter, but I made no reference that said lower grades of gasoline had different additives or was of a different make up.
What I was referring to was that when modifying a car to run more boost from the turbo or supercharger, 91 octane has a propensity to detonate. Thats exactly what the gasoline rating is, it's ability to resist detonation. In that regard, it makes 91 gas "crappy"
#104
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Even children in school here know that they sell lower octane gas beacuse of the elevation, and how it makes normal cars detonate less.
I'm not quite sure why you were trying to make your self feel smarter, but I made no reference that said lower grades of gasoline had different additives or was of a different make up.
What I was referring to was that when modifying a car to run more boost from the turbo or supercharger, 91 octane has a propensity to detonate. Thats exactly what the gasoline rating is, it's ability to resist detonation. In that regard, it makes 91 gas "crappy"
I'm not quite sure why you were trying to make your self feel smarter, but I made no reference that said lower grades of gasoline had different additives or was of a different make up.
What I was referring to was that when modifying a car to run more boost from the turbo or supercharger, 91 octane has a propensity to detonate. Thats exactly what the gasoline rating is, it's ability to resist detonation. In that regard, it makes 91 gas "crappy"
Perhaps it was this statement with the reference to 'crap' that threw me:
Seems your statement might have confused George also:
As noted above, 91 is only required at sea level so at 4400 feet there is no possibility of timing being pulled back.
#105
No offence intended at all, and there was no way I could have known you and apparently all school children in your area understand why your gas is lower in octane than other areas- and that it makes no real difference.
Perhaps it was this statement with the reference to 'crap' that threw me:
Being that S-types only require 91 octane at sea level, using it at your elevation is actually as waste. I'm fairly sure you could use 89 without encountering detonation as usually there a 2 point decrease calculated for your altitude or greater. Whether a car has FI or not has no bearing.
Seems your statement might have confused George also:
As noted above, 91 is only required at sea level so at 4400 feet there is no possibility of timing being pulled back.
Perhaps it was this statement with the reference to 'crap' that threw me:
Being that S-types only require 91 octane at sea level, using it at your elevation is actually as waste. I'm fairly sure you could use 89 without encountering detonation as usually there a 2 point decrease calculated for your altitude or greater. Whether a car has FI or not has no bearing.
Seems your statement might have confused George also:
As noted above, 91 is only required at sea level so at 4400 feet there is no possibility of timing being pulled back.
That sentence was supposed to say " so most car owners don't realize that 91 sucks, beacuse ..."
I was typing response quickly on the iPad and it got me.
I was simply pointing out that 91 is not enough when turning the boost up to a huge amount, say 30 psi. Not at the stock level beacuse none of my cars are stock.
#106
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I did not mean to be so rude, my apologies for that.
That sentence was supposed to say " so most car owners don't realize that 91 sucks, beacuse ..."
I was typing response quickly on the iPad and it got me.
I was simply pointing out that 91 is not enough when turning the boost up to a huge amount, say 30 psi. Not at the stock level beacuse none of my cars are stock.
That sentence was supposed to say " so most car owners don't realize that 91 sucks, beacuse ..."
I was typing response quickly on the iPad and it got me.
I was simply pointing out that 91 is not enough when turning the boost up to a huge amount, say 30 psi. Not at the stock level beacuse none of my cars are stock.
Is it time for the bunny with a pancake? I found him hiding away:
#108
Welcome to the forum and you sure picked a doozy of a topic for your first post! There's plenty of first person testimonials from owners (including myself) who have operated their S-types or other Jags with similar engines on 87 octane with no negative effects. This includes persons who used low octane for a very long term simply because they didn't know any different. I'd suggest you give it a try and see if you notice any reduction in power or mileage.
One thing sticks out- you mention an 18.9 cent difference in price between regular and super. That's got to be a typo. In looking at on line gas prices for your area, I see only a variation of 8-11 cents per litre. That would mean a difference of around 6 bucks per tank full or with 3 tanks per week, an extra $900 per year.
If it helps you feel any better, gas prices in Toronto are well below national average with $1.27/L for regular. I'm near Montreal right now and average prices are $1.41/L, more expensive than your super.
Perhaps I should have clarified. The 18.9 cents difference is 94 octane which in my area is only sold at Petro Canada locations which were previously Sunoco, and also at Shell. Yesterday I filled up at Esso, which their premium gas is 91 octane at 15.9 cents more than 87 octane. I paid $1.43 for it when 87 was going for $1.27. Today it dropped again to 125.9! At that difference its close to $1500/year more than using 87. At 94 octane that difference is almost $1800 per year at three fill ups per week.
I'm familiar with the websites you're talking about but they often reference the best pricing scenarios. This is a big city... in the outskirts of it had prices are as much as 3-4 cents per litre less........ but that can be a 1.5 hour drive. Where I am the spread between octane levels are 18.9 cents per litre.
#109
Oh by the way.... after filling up with 91 octane fuel I'm experiencing a misfire on cylinder 2 (obd code p0302). Interesting coincidence. Although I know its likely a coil or an injector, do you guys think its because I didn't drive the distance to find 94 octane gas? I was running low and that was an extra 10-15 mins away from my location.
#110
Oh by the way.... after filling up with 91 octane fuel I'm experiencing a misfire on cylinder 2 (obd code p0302). Interesting coincidence. Although I know its likely a coil or an injector, do you guys think its because I didn't drive the distance to find 94 octane gas? I was running low and that was an extra 10-15 mins away from my location.
Nothing to do with octane.. Do a search here on miss-fire codes... Lots of reading.. (Hint... Step one, move coils and see if the miss follows)...
Oh... Boy....
Mikey... Sit down bud, drink a cold one, then finish packing....
Oh, and thanks for getting my back over in "X" land....
Last edited by JOsworth; 09-21-2012 at 04:20 PM. Reason: need to go back to school for grammar lessons...
#112
#113
@zak...... Please stop stirring up the pot.... LOL
Nothing to do with octane.. Do a search here on miss-fire codes... Lots of reading.. (Hint... Step one, move coils and see if the miss follows)...
Oh... Boy....
Mikey... Sit down bud, drink a cold one, then finish packing....
Oh, and thanks for getting my back over in "X" land....
Nothing to do with octane.. Do a search here on miss-fire codes... Lots of reading.. (Hint... Step one, move coils and see if the miss follows)...
Oh... Boy....
Mikey... Sit down bud, drink a cold one, then finish packing....
Oh, and thanks for getting my back over in "X" land....
#114
#116
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Thanks Mikey! I'm already searching and finding lots of useful posts on here. It really does help to understand what these cars are all about, and what to expect when you can read up on other owners experiences.
Perhaps I should have clarified. The 18.9 cents difference is 94 octane which in my area is only sold at Petro Canada locations which were previously Sunoco, and also at Shell. Yesterday I filled up at Esso, which their premium gas is 91 octane at 15.9 cents more than 87 octane. I paid $1.43 for it when 87 was going for $1.27. Today it dropped again to 125.9! At that difference its close to $1500/year more than using 87. At 94 octane that difference is almost $1800 per year at three fill ups per week.
I'm familiar with the websites you're talking about but they often reference the best pricing scenarios. This is a big city... in the outskirts of it had prices are as much as 3-4 cents per litre less........ but that can be a 1.5 hour drive. Where I am the spread between octane levels are 18.9 cents per litre.
Perhaps I should have clarified. The 18.9 cents difference is 94 octane which in my area is only sold at Petro Canada locations which were previously Sunoco, and also at Shell. Yesterday I filled up at Esso, which their premium gas is 91 octane at 15.9 cents more than 87 octane. I paid $1.43 for it when 87 was going for $1.27. Today it dropped again to 125.9! At that difference its close to $1500/year more than using 87. At 94 octane that difference is almost $1800 per year at three fill ups per week.
I'm familiar with the websites you're talking about but they often reference the best pricing scenarios. This is a big city... in the outskirts of it had prices are as much as 3-4 cents per litre less........ but that can be a 1.5 hour drive. Where I am the spread between octane levels are 18.9 cents per litre.
I guess by now you've realized there's no reason or benefit in using anything higher than 91 octane so that helps with part of your issue. I can only offer you further comfort by stating that your premium at $1.43 is still cheaper than the regular in Montreal...........
One week to go as of this writing.
Last edited by Mikey; 09-22-2012 at 09:28 AM.
#117
I've been using regular.. 87 octane for sometime now.. However, I do use additives/detergents, every couple of months, just to clean out the fuel injection system, I have not seen any difference in performance. I know in other cars I've had, if it knocks... well go up to a level where you don't get the knocking.
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Mikey (09-22-2012)
#118
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#120
Hi Harry-
Thanks for your comments on the octane subject.
There's no need to add anything to the gas, it's already got all the detergents required. High compression engines don't produce any more deposits or clog up fuel injections systems any more than low compression engines.
Thanks for your comments on the octane subject.
There's no need to add anything to the gas, it's already got all the detergents required. High compression engines don't produce any more deposits or clog up fuel injections systems any more than low compression engines.
Yes, I understand that, though I've been told that the "regular" gas may not put detergents in the gas, unlike the "premium" ones typically do.
My mechanic said it's a good idea to every once in a while use the additional detergents to clean out the fuel system well and keep things in tip top shape.