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I know I’ve seen this discussion before so I’m sorry if I’m repeating this. Looked back thru several pages of threads and saw nothing. I bought my Sportage several months ago. I’ve been alternating different octanes just to see if I noticed any difference. None that I really noticed other than price. I believe the owners manual calls for regular 87 octane. Anyone have any advice on going with the higher octane as an advantage? Appreciate any replies. So far I’m loving the vehicle so far. Bought it with 4800 miles I now have 8800. So 4K miles in about 3 months. Thanks again!
 

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I know I’ve seen this discussion before so I’m sorry if I’m repeating this. Looked back thru several pages of threads and saw nothing. I bought my Sportage several months ago. I’ve been alternating different octanes just to see if I noticed any difference. None that I really noticed other than price. I believe the owners manual calls for regular 87 octane. Anyone have any advice on going with the higher octane as an advantage? Appreciate any replies. So far I’m loving the vehicle so far. Bought it with 4800 miles I now have 8800. So 4K miles in about 3 months. Thanks again!
There is no advantage to using higher octane fuel unless the vehicle requires it. The vehicle is calibrated and designed to run off the manufacturers octane recomendations. Just run good quality fuel in 87 octane, and not the stop here and fill up to get a free set of blue glasses type place. I've used Sunoco for years and have never had fuel related issues in any vehicle.
 

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If you demand every last horse power the engine can produce use premium unleaded of at least 91 octane.
If you can live and be happy without squeezing out every last pony, listen to Ricbrk, above.....
 
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If you demand every last horse power the engine can produce use premium unleaded of at least 91 octane.
If you can live and be happy without squeezing out every last pony, listen to Ricbrk, above.....
Octane has nothing to do with power -- this is just a myth. Octane is the measure of how much compression a fuel can withstand before igniting. When your car is designed for 87 octane like ours, the compression ratio is left at a point where you get no pre-ignition. So, you are not going to get ANY extra ponies with 91 octane fuel. I just don't know why so many people are misinformed....

 

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rvoll_ Like the old saying: you can lead a horse to water, but you cant make him drink.....
 

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rvoll_ Like the old saying: you can lead a horse to water, but you cant make him drink.....
In our society today, whether it's cars or politics, so many people believe things that aren't true or aren't science. I guess it just makes them feel better about their choices. So my comments will never convince people who have ingrained beliefs. Personally, I like it when someone shows that I'm wrong through science and controlled testing (and not anecdote or something they've read on the internet) because then I've learned something new. My posts are not for these people who don't listen to truth -- it is for the others who read forums like this who don't know the science and can learn from it or just even think about it when someone makes a statement. I've had a BMW that did get added power through the use of premium fuel, but it was designed to do that AND it was in the manual. In essence, in that car, the knock sensor led to a retard in the spark and other adjustments. The Sportage -- and most of today's cars -- were not designed to do that. And if you understand the technology, you'd see why.

So I'll continue to lead those horses to water on the slight and remote chance their minds will open up in the future....
 
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Use a Top Tier name brand gas and you're done. The owners manual should specify that as they do for GDI engines but regardless. Use Top Tier Gas whenever possible, its cleaner formulation.
 

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To me, the better question is whether to fuel your engine with non-ethanol or ethanol blend gas.
More than 98% of the gas in the U.S. uses 10% ethanol gas. Because of that, I'm not sure how much of an issue this is.
 
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Use a Top Tier name brand gas and you're done. The owners manual should specify that as they do for GDI engines but regardless. Use Top Tier Gas whenever possible, its cleaner formulation.
Totally agree. The manual does say that if you use Top Tier gas you DON'T need to use a fuel additive. Technically, using more additives than are found in Top Tier gas does practically nothing for your engine. For the last couple of decades, I have never used any fuel additives but absolutely make sure I use Top Tier gas....
 
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Totally agree. The manual does say that if you use Top Tier gas you DON'T need to use a fuel additive. Technically, using more additives than are found in Top Tier gas does practically nothing for your engine. For the last couple of decades, I have never used any fuel additives but absolutely make sure I use Top Tier gas....
I run Top Tier in a SxS style ATV and they have a spark arrester screen in the muffler to clean. I have had it out twice in over 10,000km (high for a SxS) and absolutely clean. 99% of the gas was top tier and when it wasn't its mixing in with what top tier is still in it. If everyone used clean gas there would be fewer fuel system issues I am sure and O2 sensor issue. The cost is pretty much the same, even if I have to drive further for it I still do on route to where I am going.
 
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The higher the octane the slower the fuel burns and the less chance of detonation (spark knock).

If the engine detonates or knocks, the knock sensors (really microphones) pick up the noise and then retard the timing to stop the destructive issue. All modern vehicles incorporate knock sensors.

When you pull spark (retarding the timing) the power of the engine is decreased under WOT conditions.

Reduced power = less horsepower being produced.

Today it is all controlled by computers.

Just trying to keep things simple for the OP......

Before you slam and insult other people's knowledge, please climb off your high horse and take an Engine Design 101 class!

119627
 
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More than 98% of the gas in the U.S. uses 10% ethanol gas. Because of that, I'm not sure how much of an issue this is.
I didn't say it was an issue. I said the better question to me is whether to use ethanol blends or non-ethanol.

With the suppressed cost of ethanol blends, there really isn't any cost savings to using non-ethanol gas. But what are the drawbacks/benefits to using or not using ethanol? That's what I am asking.
 

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In the turbo KIA (as well as other manufacturers) engine failures have occurred from low-speed detonation. Because the small-diameter turbine spools up rapidly with even slight throttle, and because the transmission is programmed for delayed downshift at slow vehicle speed to enhance mileage, you will get into a situation where you want to accelerate lightly or maintain speed on an incline at speeds below 40 MPH, and it is possible that with regular gas that there will be a tendency for detonation. For this reason and because mid-grade fuel is a mixture of Regular and Premium, thereby containing some of the premium additives, I have been using at least mid-grade in mine for the whole time I've had it. I heard the heavy 'thumping' sound in the above situation with Regular gas but not since I've been using at least mid-grade of 89 or 90 octane. Because we have to use E10 in my area, I also use a fuel stabilizer for alcohol fuels that is also a fuel system cleaner. This is critical because you must avoid carbon build-up in the combustion chambers as it artificially increases the compression ratio, plus it will glow and promote pre-ignition. These two things must be prevented in order to have a long engine life. The worse that can happen is you'll waste a few dollars with every fill-up. The best that can happen is your car will still be running smoothly in a few years when you trade it in.
I don't see where it's a matter for such spirited discussion. So what if some of us spend more for gas? Its not a problem to anyone else and shouldn't get such pedantic comments. Plus, I actually believe this regimen, along with using the best synthetic oil I can get, will keep my very spirited SX humming for the life of the vehicle.
As for the delayed downshift, just be alert for this situation, and with the manual shifting possible in the SX, just flick the downshift paddle when you feel like it's 'lugging'.
 

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The higher the octane the slower the fuel burns and the less chance of detonation (spark knock).

If the engine detonates or knocks, the knock sensors (really microphones) pick up the noise and then retard the timing to stop the destructive issue. All modern vehicles incorporate knock sensors.

When you pull spark (retarding the timing) the power of the engine is decreased under WOT conditions.

Reduced power = less horsepower being produced.

Today it is all controlled by computers.

Just trying to keep things simple for the OP......

Before you slam and insult other people's knowledge, please climb off your high horse and take an Engine Design 101 class!

View attachment 119627
I'm glad you completed your class, but your analysis doesn't apply here. When you DESIGN an engine to run on 87 octane, THE SPARK IS NOT RETARDED, since the knock sensor is not engaged with 87 octane as it doesn't reach ECM minimums. Hence, you'll get no increase in horsepower when you use higher octane. When you DESIGN an engine to run on 87 octane, you maximize performance through programming the ECM and set the compression ratio (the main factor in needing higher octane fuels) to a maximum level. It is there because there are cases where you get inferior fuel and the engine must be protected. There are engines DESIGNED to use higher octane and then the knock sensor retards the spark among other adjustments when lower octane is used. Your assumption is clearly wrong. So, before you talk about "high horses", I'd look in the mirror and check with one of your more knowledgeable teachers. Give them the information I just provided to you and see what they say. I have a few advanced degrees myself, but prefer not to use them as a crutch to provide incomplete information. Engine design has changed since you completed your class in 1997 primarily because of the increased sophistication of the computers used in today's cars and the super computers used for engine design. If you have a chance to visit a major manufacturer's engine design facility, I'd suggest you do so. Many of the things I thought were true two decades ago, are just no longer true today.

P.S. Do you know how the knock sensor works in combination with the ECM? The knock sensor constantly puts out voltages, but the ECM only adjusts the spark when certain minimums are reached. I haven't modified a Sportage ECM, but I have worked with tuners on a couple of my track cars. All courses you take have limitations and while you learned the engine design basics in that course, you would not have covered ECM maximization as that is an advanced topic. The only reason I know about it is because of my track experience and work with engine modifiers.
 

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In the turbo KIA (as well as other manufacturers) engine failures have occurred from low-speed detonation. Because the small-diameter turbine spools up rapidly with even slight throttle, and because the transmission is programmed for delayed downshift at slow vehicle speed to enhance mileage, you will get into a situation where you want to accelerate lightly or maintain speed on an incline at speeds below 40 MPH, and it is possible that with regular gas that there will be a tendency for detonation. For this reason and because mid-grade fuel is a mixture of Regular and Premium, thereby containing some of the premium additives, I have been using at least mid-grade in mine for the whole time I've had it. I heard the heavy 'thumping' sound in the above situation with Regular gas but not since I've been using at least mid-grade of 89 or 90 octane. Because we have to use E10 in my area, I also use a fuel stabilizer for alcohol fuels that is also a fuel system cleaner. This is critical because you must avoid carbon build-up in the combustion chambers as it artificially increases the compression ratio, plus it will glow and promote pre-ignition. These two things must be prevented in order to have a long engine life. The worse that can happen is you'll waste a few dollars with every fill-up. The best that can happen is your car will still be running smoothly in a few years when you trade it in.
I don't see where it's a matter for such spirited discussion. So what if some of us spend more for gas? Its not a problem to anyone else and shouldn't get such pedantic comments. Plus, I actually believe this regimen, along with using the best synthetic oil I can get, will keep my very spirited SX humming for the life of the vehicle.
As for the delayed downshift, just be alert for this situation, and with the manual shifting possible in the SX, just flick the downshift paddle when you feel like it's 'lugging'.
Man, I don't know where to start. But here's an article on LSPI that could inform you. Hint: It's not because of the octane. There is an assumption that higher octane gas has more additives. Any gas that adheres to the Top Tier spec, regardless of octane, has the same basic additives. There are some marketing people at some oil companies that have an additional additive added to premium gas, but there is absolutely no evidence it actually does anything for you. If you do a chemical analysis of gas, you'll see that all gas has the same amount of "power".
In regards to a "spirited" discussion, this is, in fact, a car forum. Isn't that the proper place to have technical discussions? And yes, you can spend your money as you wish. But some of these beliefs are just not true. I think some of this misinformation comes from the fact that many of us old guys used to have engines that did have knocking and pinging and we did put in higher octane gas to solve this problem. But that was a long time ago when ECM's and engine design was not what it is today. In the last couple of decades, I have never had a car with "carbon build-up", and I don't use higher octane or fuel cleaners. (I used to use them regularly). I know I'm never going to convince you guys basis a scientific and technical analysis, but I'll continue to try because I absolutely hate misinformation.
Now, I'd be happy to be wrong and learn something if you have a qualified study I can review (and not some ramblings on a forum....)

 

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Wow....did this thread go sideways!

You guys don't read and comprehend very well.

Yes, it was 'designed' to run on 87 octane. Yes, engine control algorithm's look at many variables to control engine operations. Knock sensors are one of the most sensitive sensors. That's why they are used by Kia for the dreaded debris issues. They use the knock sensors as a tool to control various operating conditions.

When tested by the OEM for Big Government and advertising purposes. there are' ideal conditions' in the test cell. Standard pump fuel is not used by OEM's. If you dyno an engine in the vehicle it will never match advertised H.P., but it needs to be within a specified percentage limit. Ford got into trouble a few years ago with this. Only engine I know of (N/A) that puts out as advertised HP is an LS7. It is SAE Certified at 505 HP at 7K RPM.

If you want the maximum power possible as a owner, at all times, under most operating conditions (atmospheric pressure variances comes into play on a naturally aspirated engines, aka non-turbo) you should use premium fuel. If you don't care, use 87, it won't hurt anything. That is the point!
 

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If you want the maximum power possible as a owner, at all times, under most operating conditions (atmospheric pressure variances comes into play on a naturally aspirated engines, aka non-turbo) you should use premium fuel. If you don't care, use 87, it won't hurt anything. That is the point!
I don't know how many ways I can say this, BUT THIS IS JUST NOT TRUE FOR OUR CAR. This subject has been researched by people far more knowledgeable than you or I -- and I read much of the research. It is confusing because there are many cars where this is true. It all depends on the design of the engine and the way the ECM has been programmed. What happens is that when you put in premium, the car doesn't know that fact. So the ECM constantly tries to improve performance by pushing the limits. If you get a high performance vehicle with a large engine, then there will be a difference in the majority of cases. But in the tests I've seen for turbocharged small 4 cylinder vehicles, there has been no added performance WHEN THE MANUFACTURER SAYS TO USE 87 GAS. To make the generalization that premium will ALWAYS give you higher power FOR OUR CAR is just wrong. Technically, you're not going to hurt your car with premium gas either. You are just wasting your money for no added benefit.

Your statement that 87 gas won't hurt anything is important. Those who use premium gas so their engines will last longer are clearly wrong and you and I would agree on that. So, for argument's sake, let's say you do have a power increase with premium fuel. The first question is how much of an increase will it be. In the testing I've seen for other cars WHERE THE MANUAL SAYS THAT PREMIUM WILL GIVE YOU ADDED HP, the increase is in the range of 5%, i.e., 20hp for a 400hp engine. In these engines, when you use 87 gas, your car is detuned. (It is NOT detuned for our car). So let's say that you can achieve half that result, or 2.5% or about 6hp on the 2.0 turbo. Because of engine dynamics, that 6 hp will only be fully useful when the engine is pushed -- not when you are driving normally. So, you MIGHT get it when passing a car or accelerating on the freeway. The question for the owner then comes down to how much extra money do you want to spend for a slight performance increase useful only a small part of driving time.

I've seen a few tests where using premium actually decreases power. I have trouble believing this, but they were done by competent organizations and mostly in Hondas. It seems you can program the ECM to provide more economy with higher octane gas and this actually decreases hp. This strategy would make sense if you are selling economy vehicles. I don't know if Kia does this and until our car is tested, there's no way of getting this answer.

Much of what happens when we buy a car, given that it is one of the most expensive purchases by most of us, is that we are human and it affects our psychology. We want to treat it well as if it was a member of the family. So we clean it often, we buy "jewelry" for it, and we "feed" it the very best. Is this really necessary? No, but it makes us feel better. I've changed the Kia logos and put a trim ring on my steering wheel. Does this make the car perform better? Again, we both agree that premium will not make your engine last longer and your car just doesn't need it.

I guess I just don't know how you can make your generalizations with the abundance of tests by competent organizations saying there is NO benefit for using premium fuel in cars designed to use regular. They clearly don't agree with you. Don't get me wrong, your argument does make "common sense" based on generalizations. And, it was exactly what I believed over a decade ago when I retired and had the time to research issues like this. The research changed my mind from the simple "common sense" argument, to a more sophisticated understanding.

In the end, what's important here, is that there is no benefit to the HEALTH of your car in using premium fuel. And we both agree on that. There might be a very slight power increase if your generalizations are true for our specific car, but is that worth all of the extra money you pay for it? For me, after doing all of my research, tuning track cars, and actually visiting engine manufacturing facilities and talking with the engineers, I just don't buy the generalization FOR OUR CAR. So, are you willing to spend all of that money for the life your compact, economy SUV just on the speculation that there might be a power increase that's only usable a small part of your driving time????? Hmmmm.... The answer for me is clearly no....
 

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Discussion Starter · #19 ·
I don't know how many ways I can say this, BUT THIS IS JUST NOT TRUE FOR OUR CAR. This subject has been researched by people far more knowledgeable than you or I -- and I read much of the research. It is confusing because there are many cars where this is true. It all depends on the design of the engine and the way the ECM has been programmed. What happens is that when you put in premium, the car doesn't know that fact. So the ECM constantly tries to improve performance by pushing the limits. If you get a high performance vehicle with a large engine, then there will be a difference in the majority of cases. But in the tests I've seen for turbocharged small 4 cylinder vehicles, there has been no added performance WHEN THE MANUFACTURER SAYS TO USE 87 GAS. To make the generalization that premium will ALWAYS give you higher power FOR OUR CAR is just wrong. Technically, you're not going to hurt your car with premium gas either. You are just wasting your money for no added benefit.

Your statement that 87 gas won't hurt anything is important. Those who use premium gas so their engines will last longer are clearly wrong and you and I would agree on that. So, for argument's sake, let's say you do have a power increase with premium fuel. The first question is how much of an increase will it be. In the testing I've seen for other cars WHERE THE MANUAL SAYS THAT PREMIUM WILL GIVE YOU ADDED HP, the increase is in the range of 5%, i.e., 20hp for a 400hp engine. In these engines, when you use 87 gas, your car is detuned. (It is NOT detuned for our car). So let's say that you can achieve half that result, or 2.5% or about 6hp on the 2.0 turbo. Because of engine dynamics, that 6 hp will only be fully useful when the engine is pushed -- not when you are driving normally. So, you MIGHT get it when passing a car or accelerating on the freeway. The question for the owner then comes down to how much extra money do you want to spend for a slight performance increase useful only a small part of driving time.

I've seen a few tests where using premium actually decreases power. I have trouble believing this, but they were done by competent organizations and mostly in Hondas. It seems you can program the ECM to provide more economy with higher octane gas and this actually decreases hp. This strategy would make sense if you are selling economy vehicles. I don't know if Kia does this and until our car is tested, there's no way of getting this answer.

Much of what happens when we buy a car, given that it is one of the most expensive purchases by most of us, is that we are human and it affects our psychology. We want to treat it well as if it was a member of the family. So we clean it often, we buy "jewelry" for it, and we "feed" it the very best. Is this really necessary? No, but it makes us feel better. I've changed the Kia logos and put a trim ring on my steering wheel. Does this make the car perform better? Again, we both agree that premium will not make your engine last longer and your car just doesn't need it.

I guess I just don't know how you can make your generalizations with the abundance of tests by competent organizations saying there is NO benefit for using premium fuel in cars designed to use regular. They clearly don't agree with you. Don't get me wrong, your argument does make "common sense" based on generalizations. And, it was exactly what I believed over a decade ago when I retired and had the time to research issues like this. The research changed my mind from the simple "common sense" argument, to a more sophisticated understanding.

In the end, what's important here, is that there is no benefit to the HEALTH of your car in using premium fuel. And we both agree on that. There might be a very slight power increase if your generalizations are true for our specific car, but is that worth all of the extra money you pay for it? For me, after doing all of my research, tuning track cars, and actually visiting engine manufacturing facilities and talking with the engineers, I just don't buy the generalization FOR OUR CAR. So, are you willing to spend all of that money for the life your compact, economy SUV just on the speculation that there might be a power increase that's only usable a small part of your driving time????? Hmmmm.... The answer for me is clearly no....
Very well said. Thank you for taking the time to explain all that. Totally makes sense. Regular 87 octane it is!
 

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Very well said. Thank you for taking the time to explain all that. Totally makes sense. Regular 87 octane it is!
Just be sure you ALWAYS use Top Tier gas!!!
 
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