View Poll Results: WHICH OCTANE DO YOU USE?
87
15
15.15%
88
0
0%
89
13
13.13%
91
31
31.31%
93
41
41.41%
Multiple Choice Poll. Voters: 99. You may not vote on this poll
Which Octane Do You Use?
12-13-2003, 11:12 PM
#27
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Originally posted by Ole Spiff
I'm comfortable using regular since the manual says it's safe to do so.
I'm comfortable using regular since the manual says it's safe to do so.
12-14-2003, 12:11 AM
#28
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Originally posted by matt
I thought the manual calls for Premium?
I thought the manual calls for Premium?
Here it is from page 4-2 of the manual:
"Your Mazda will perform best with fuel listed in the table.
{ Fuel : Octane Rating * (Anti-knock index) }
{ Premium unleaded fuel : 91 [ (R+M)/2 method] or above (96 RON or above) }"
{} above is in the table and the following is right below the table:
"You may use a regular unleaded fuel with Octane Rating from 87 to 90 (91 to 95 RON) but this will slightly reduce performance."
---
rx8cited
Last edited by rx8cited; 12-14-2003 at 12:46 AM.
12-14-2003, 02:28 AM
#29
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Originally posted by rx8cited
---
Here it is from page 4-2 of the manual:
"Your Mazda will perform best with fuel listed in the table.
{ Fuel : Octane Rating * (Anti-knock index) }
{ Premium unleaded fuel : 91 [ (R+M)/2 method] or above (96 RON or above) }"
{} above is in the table and the following is right below the table:
"You may use a regular unleaded fuel with Octane Rating from 87 to 90 (91 to 95 RON) but this will slightly reduce performance."
---
rx8cited
---
Here it is from page 4-2 of the manual:
"Your Mazda will perform best with fuel listed in the table.
{ Fuel : Octane Rating * (Anti-knock index) }
{ Premium unleaded fuel : 91 [ (R+M)/2 method] or above (96 RON or above) }"
{} above is in the table and the following is right below the table:
"You may use a regular unleaded fuel with Octane Rating from 87 to 90 (91 to 95 RON) but this will slightly reduce performance."
---
rx8cited
I HAVE 2 QUESTIONS... EXPLAIN WHAT "RON" IS WHEN IT COMES TO THE OCTANE ISSUE.... AND IF IT SAYS TO USE PREMIUM FUEL 91 [ (R+M)/2 method] or above...... THIS MEANS 93 IS PERFECTLY SAFE... CORRECT? WHAT ABOUT THE FLOODING ISSUE AND HIGH OCTANE FUEL, IS THERE TRUTH IN THAT?
-ERIK
12-14-2003, 08:22 AM
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RON would the "R" in the "(R+M)/2" equation; the Research Octane Number". It's the "fantasy-land" octane number obtained in a lab under low-speed conditions. The "M" in the equation is the MON, the Motor Octane Number which is obtained under higher demand conditions and therefore a lower number. And since 93 is less apt to knock than 91, yes 93 is "safe" as compared to 91 Average Knock Indicator (AKI).
Regarding flooding, you'd need a response from someone a lot more engine-savey than I to know for sure but, having worked as a chemist for almost 30 years, I can take an educated guess. My guess is that there's probably not enough difference in the vapor pressure or the flash point of 87 vs 93 octane gasoline to require different carburation for one vs. the other. I suspect that engines would flood or not-flood indepedent of the octane rating of the gasoline being used for fuel. You could stretch and say that perhaps they'd be a bit more fuel-rich because the computer controls are compensating for the lower octane and thus a bit more apt to flood, but since flooding happens on cold-starts, you'd assume the computer would be choking the hell out of the fuel-mix anyway, independent of octane.
Answer is, I don't know the answer on the flooding question, but I doubt that 87 octane would be the underlying cause.
Having said that, I want to go on record that I wouldn't put anything less than 91 in my 8. There is no 91 here in Texas, so I run 93. If I drive 1500 miles per month (which is close to my average) and the 93 costs $0.20 more than the 87 octane, and I assume 15 mpg (and that's low based on what I've seen so far), then that's 100 gallons of fuel at $0.20 per gallon; or $20 per month to protect the engine and to ensure that the I'm doing what I can do to allow the engine to run as designed. I spend $20 a month on soda pop from the machine at work. Not a huge sum, even over the life of the car.
I like the statement above that says "use what you're comfortable with." If you like 87 and like that $20 a month, it's not hurting me any. I just like knowing I'm doing what I can to give my 8 every chance to be a reliable, long-life, dependable machine.....
Regarding flooding, you'd need a response from someone a lot more engine-savey than I to know for sure but, having worked as a chemist for almost 30 years, I can take an educated guess. My guess is that there's probably not enough difference in the vapor pressure or the flash point of 87 vs 93 octane gasoline to require different carburation for one vs. the other. I suspect that engines would flood or not-flood indepedent of the octane rating of the gasoline being used for fuel. You could stretch and say that perhaps they'd be a bit more fuel-rich because the computer controls are compensating for the lower octane and thus a bit more apt to flood, but since flooding happens on cold-starts, you'd assume the computer would be choking the hell out of the fuel-mix anyway, independent of octane.
Answer is, I don't know the answer on the flooding question, but I doubt that 87 octane would be the underlying cause.
Having said that, I want to go on record that I wouldn't put anything less than 91 in my 8. There is no 91 here in Texas, so I run 93. If I drive 1500 miles per month (which is close to my average) and the 93 costs $0.20 more than the 87 octane, and I assume 15 mpg (and that's low based on what I've seen so far), then that's 100 gallons of fuel at $0.20 per gallon; or $20 per month to protect the engine and to ensure that the I'm doing what I can do to allow the engine to run as designed. I spend $20 a month on soda pop from the machine at work. Not a huge sum, even over the life of the car.
I like the statement above that says "use what you're comfortable with." If you like 87 and like that $20 a month, it's not hurting me any. I just like knowing I'm doing what I can to give my 8 every chance to be a reliable, long-life, dependable machine.....
12-14-2003, 11:56 AM
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Another point to remember is gas prices are not the same everywhere. Texas has quite a bit lower prices than here in California. We get gouged all the time here and especially during a holiday when they know everybody is going to drive more, they'll up the price of gas 10-20 cents a gallon practically overnight.
Last time my wife was in Texas she said gas prices there were almost 50 cents cheaper per gallon than here. Southern California is a commuter community so we spend a lot of time on the road here.
All that notwithstanding I didn't switch to regular until after running some tests to see if it mattered enough to switch. It wasn't just money savings; my car actually performed better than with premium. It is more responsive, smoother to drive, easier to start in first gear and idles smoother. The dollar savings is just a bonus; I have the money to afford premium.
BTW...I love this car. It is such a great feeling to be in it and driving it. I've had it since July and the thrill still hasn't worn off. :D
Last time my wife was in Texas she said gas prices there were almost 50 cents cheaper per gallon than here. Southern California is a commuter community so we spend a lot of time on the road here.
All that notwithstanding I didn't switch to regular until after running some tests to see if it mattered enough to switch. It wasn't just money savings; my car actually performed better than with premium. It is more responsive, smoother to drive, easier to start in first gear and idles smoother. The dollar savings is just a bonus; I have the money to afford premium.
BTW...I love this car. It is such a great feeling to be in it and driving it. I've had it since July and the thrill still hasn't worn off. :D
12-14-2003, 12:34 PM
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You're right. We have probably some of the cheapest gasoline around. I'm paying about $1.55 for the 93 octane, sometimes a few cents less. 87 octane would go for about $1.35 or so. At first glance, I'd have explained the lower rates here on state taxes but the rate is $.20 per gallon in Texas vs. $0.18 per gallon in California. Must be in part what the market will bear. We're close to refineries here in Houston, so there's less spent on hauling the stuff but you can haul a tanker load of gasoline cross-country for less than $0.25 per gallon (probably a lot less) and some gasoline is actually pipelined. I'd assume they must move some by rail as well, which is even cheaper.
Regarding a car-commuter-society, Houston's probably on a par with LA. Before you go defending Los Angeles record, I don't mean as many cars or as many miles of road or as long traffic-jams. I mean that darn near nobody here would take a bus on a bet. There are no trains and there's probably one taxi for every 2,000 people, if that. We go everywhere by car. Add to that the fact that Houston's about 60 by 60 miles square and there's a lot of cars on the road (and at the pump.)
I'm glad the regular gasoline is working for you. Like it's been said before, "if it works, don't fix it."
Regarding a car-commuter-society, Houston's probably on a par with LA. Before you go defending Los Angeles record, I don't mean as many cars or as many miles of road or as long traffic-jams. I mean that darn near nobody here would take a bus on a bet. There are no trains and there's probably one taxi for every 2,000 people, if that. We go everywhere by car. Add to that the fact that Houston's about 60 by 60 miles square and there's a lot of cars on the road (and at the pump.)
I'm glad the regular gasoline is working for you. Like it's been said before, "if it works, don't fix it."
12-14-2003, 01:08 PM
#33
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The gasoline in California is at the price it is for various reasons.
Our minimum wage here is substantiually higher than that of the Federal minimum wage, which means we get to deal with more inflation with day to day expenses.
Next off, we have THE stricted emissions regulations set forth by our state government. It is so damn strict, that car dealerships are only allowed to trade cars with California State Dealerships, unlike places like Jersey that can trade with Michigan, hell, Florida if they wanted to send drivers that far. Our gasoline here is "specially formulated" to comply with our emissions regulations. Remember the oil refinery issues back in 99? That was when a pipe broke in San Francisco or some place in the Bay Area. Over night, gasoline prices flew up significantly in California. There were plenty of neighboring states that had plenty of oil, and they were willing to sell us some at a substansually lower price than that of even our regular costs, but due to emissions regulations, we were stuck bent over our bonnets without vasoline.
Another factor...we have too many well off people in this State. Too many people with Mercedez, BMW's, Lexus's and other cars that require Premium fuels. So from each bit of raw fuels, they can only produce so many different oil variants. With that in mind, they took a step down from our former 92 octane and serve 91 octane now.
Our minimum wage here is substantiually higher than that of the Federal minimum wage, which means we get to deal with more inflation with day to day expenses.
Next off, we have THE stricted emissions regulations set forth by our state government. It is so damn strict, that car dealerships are only allowed to trade cars with California State Dealerships, unlike places like Jersey that can trade with Michigan, hell, Florida if they wanted to send drivers that far. Our gasoline here is "specially formulated" to comply with our emissions regulations. Remember the oil refinery issues back in 99? That was when a pipe broke in San Francisco or some place in the Bay Area. Over night, gasoline prices flew up significantly in California. There were plenty of neighboring states that had plenty of oil, and they were willing to sell us some at a substansually lower price than that of even our regular costs, but due to emissions regulations, we were stuck bent over our bonnets without vasoline.
Another factor...we have too many well off people in this State. Too many people with Mercedez, BMW's, Lexus's and other cars that require Premium fuels. So from each bit of raw fuels, they can only produce so many different oil variants. With that in mind, they took a step down from our former 92 octane and serve 91 octane now.
12-15-2003, 04:51 AM
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For more than you'd ever want to know about California gasoline and cost-drivers in the Southern California market, I'd suggest the following reference...
http://www.eia.doe.gov/pub/oil_gas/p...cagasoline.pdf
It does a very good job of backing out the fixed costs (such as cost of crude) and assigning the higher-than-national-average costs, in large part, to the fact that California is phasing out MTBE and moving to ethanol as the oxygen-source in their fuel -- this transition is complicated by the fact that these two types of gasoline cannot be mixed. If I own a station and I've switched my storage tanks to ethanol-treated gasoline, it doesn't matter how much excess MBTE gasoline is out there, I'm forced to buy the ethanol-blended stocks (since the two fuels cannot be mixed). Add to that the fact that ethanol does raise the vapor pressure of gasoline and that, to offset said rise in vapor pressure, California "summer-blend" which they start making in February, has the lighter components such as butane stripped out (so as the drop the vapor pressure back down to where it would have been if no ethanol had been added) and you've got an added cost. Given that these "light ends" make up about 5 to 10% of the volume of refined petroleum (gasoline feedstock) the net effect of leaving them out of the gasoline is that you've encountered a 5 to 10 percent drop in refining capacity.
Take into account that MBTE was added at a rate of 10 to 11 percent vs. ethanol that is added at a rate of closer to 5 percent and you've lost another five or six percent in refinery-delivery-capacity. The report in the link above states that the net effect of these cost drivers was enough to cause California gasoline to rise $0.625 per gallon between December 9, 2002 and March 17, 2003. The national average rise during the same time period was $0.368 per gallon.
Interesting, if somewhat tedious reading.....
http://www.eia.doe.gov/pub/oil_gas/p...cagasoline.pdf
It does a very good job of backing out the fixed costs (such as cost of crude) and assigning the higher-than-national-average costs, in large part, to the fact that California is phasing out MTBE and moving to ethanol as the oxygen-source in their fuel -- this transition is complicated by the fact that these two types of gasoline cannot be mixed. If I own a station and I've switched my storage tanks to ethanol-treated gasoline, it doesn't matter how much excess MBTE gasoline is out there, I'm forced to buy the ethanol-blended stocks (since the two fuels cannot be mixed). Add to that the fact that ethanol does raise the vapor pressure of gasoline and that, to offset said rise in vapor pressure, California "summer-blend" which they start making in February, has the lighter components such as butane stripped out (so as the drop the vapor pressure back down to where it would have been if no ethanol had been added) and you've got an added cost. Given that these "light ends" make up about 5 to 10% of the volume of refined petroleum (gasoline feedstock) the net effect of leaving them out of the gasoline is that you've encountered a 5 to 10 percent drop in refining capacity.
Take into account that MBTE was added at a rate of 10 to 11 percent vs. ethanol that is added at a rate of closer to 5 percent and you've lost another five or six percent in refinery-delivery-capacity. The report in the link above states that the net effect of these cost drivers was enough to cause California gasoline to rise $0.625 per gallon between December 9, 2002 and March 17, 2003. The national average rise during the same time period was $0.368 per gallon.
Interesting, if somewhat tedious reading.....
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