Best Regular Unleaded Gas
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I'm confused here folks. So is using premium gasoline going to lead to problems in my engine? My Acura Integra calls for Premium and that is what I have been using. So am I clogging up my engine by doing this? I have been trying to figure this out by researching posts here but I just don't get it. Will I get more life out of my engine if I use a lower octane even though my engine calls for premium. Or is this a thing where if you have a car that calls for regular gas just go with the regular or you will leave deposits with a higher octane.
BTW I have been using Shell V Power since it came out
Thanks for the help OCB
BTW I have been using Shell V Power since it came out
Thanks for the help OCB
Why is that? The more I read here the more confused I get.
quote:
Originally posted by Chimay:
I have been switching between Shell V Power, and BP 93 octane in my V8 Toyota. I have also heard that you should not use the same brand of gas more than three tanks in a row.
I went to the Nissan dealer asked about what is the best fuel for milage they said 89 octane. So I tryed the higher grade and will test it against the 87 Costco gas with FP.
Terry, I take issue with some of the points that you've raised. First, it's a fact that major gasloline suppliers put more detergents into their premium grade gasolines than their regular grades. Good examples are Shell and Amoco. More detergents do help keep engines cleaner (don't know about helping to clean up dirty engines). Now, gasolines differ markedly in terms of composite makeup from region to region, but the detergents stay the same.
However, regarding the anti-knock grading of gas, there is a detriment to using gasoline that is of low octane quality which forces your ECM to retard timing. And that detriment is not just "less power," or "worse mileage." It's the fact that when the ECM has to retard the timing, there is unburned fuel vapor that stays in the cylinder, washing the cylinder walls and piston ring lands of oil and causing piston temps to rise. This, naturally, increases wear on the piston crown and the top of the cylinder, not to mention any problems that might occur when there is predetonation.
To all who post on this board and say that they get along just fine on regular gas when the manufacturer recommends premium, I say are you listening for predetonation? Do you know what it sounds like in your engine? Or are you driving around with the radio blaring (like most of us)? Because if you aren't listening for predetonation, then you really can't say that there is no difference in your car between regular gas and premium.
None if it really makes a difference if you're only planning on keeping the car for 2 years, or if you lease. But if you're planning on keeping your car for a while, remember this: ECMs are NOT designed to combat predetonation caused by deposits. They'll retard the timing to a certain point, but if you have hot deposits in a cylinder, you can still get knocking if you use 87 octane gas-simply because the computer will only retard the timing so far. And that's bad for your engine, and the longevity of your car.
Personally (and, of course, this is just my opinion), I think that everyone has the misconception that if the engine has a computer, there is no way that the engine can knock. That's bullcaca. Use good quality gas, listen for predetonation, and protect your $20000.00 + investment by using a gas that has an adequate octane grade!
fitz
However, regarding the anti-knock grading of gas, there is a detriment to using gasoline that is of low octane quality which forces your ECM to retard timing. And that detriment is not just "less power," or "worse mileage." It's the fact that when the ECM has to retard the timing, there is unburned fuel vapor that stays in the cylinder, washing the cylinder walls and piston ring lands of oil and causing piston temps to rise. This, naturally, increases wear on the piston crown and the top of the cylinder, not to mention any problems that might occur when there is predetonation.
To all who post on this board and say that they get along just fine on regular gas when the manufacturer recommends premium, I say are you listening for predetonation? Do you know what it sounds like in your engine? Or are you driving around with the radio blaring (like most of us)? Because if you aren't listening for predetonation, then you really can't say that there is no difference in your car between regular gas and premium.
None if it really makes a difference if you're only planning on keeping the car for 2 years, or if you lease. But if you're planning on keeping your car for a while, remember this: ECMs are NOT designed to combat predetonation caused by deposits. They'll retard the timing to a certain point, but if you have hot deposits in a cylinder, you can still get knocking if you use 87 octane gas-simply because the computer will only retard the timing so far. And that's bad for your engine, and the longevity of your car.
Personally (and, of course, this is just my opinion), I think that everyone has the misconception that if the engine has a computer, there is no way that the engine can knock. That's bullcaca. Use good quality gas, listen for predetonation, and protect your $20000.00 + investment by using a gas that has an adequate octane grade!
fitz
OCB - Some folks will run premium gas with the anticipation that the additional detergent adds will clean CCD deposits.
Terry's point is that this situation may actually add to deposits due to the higher octane rated gas not combusting efficiently.
If your engine requires premium gas, by all means run it & not to worry.
The use of FP, or to a lesser extent, Techron or Redline SI, will help clean up the deposits.
Fitz,
My understanding is that certain gasoline marketers do add more detergents to their premium gas. Other marketers add the same amount of detergents, and with some brands, this is a superior amount in all octane grades. The EPA requires a certain level of detergents in gasoline to help keep the cars emissions under control, but some gasoline marketers add more detergents for competitive reasons.
I don't think there will be unburned fuel in the cylinder because the knock sensor will advance or retard the spark to prevent detonation in every particular driving sequence. There will be no predetonation because the knock sensor will not allow it.
Some engines build up carbon deposits in the combustion chamber. These glow red hot, cause ignition of the fuel before the spark fires, and even those engines are built for 87 AKI the engine needs higher octane to prevent predetonation because of this. It is a carbon problem, not a gasoline problem or knock sensor problem. Spending for higher octane gasoline is a band-aid approach. Cleaning the carbon from the combustion chamber is the right way to deal with this.
A couple of years ago, "Car & Driver" magazine tested several cars on the dyno with different grades of gasoline. They found that engines built for high octane gasoline had power and fuel consumption losses on regular gas that just about evened out the cost savings. Engines built for regular gas had no power improvement on high octane gasoline within the error range of the instruments on the dyno.
Ken
My understanding is that certain gasoline marketers do add more detergents to their premium gas. Other marketers add the same amount of detergents, and with some brands, this is a superior amount in all octane grades. The EPA requires a certain level of detergents in gasoline to help keep the cars emissions under control, but some gasoline marketers add more detergents for competitive reasons.
I don't think there will be unburned fuel in the cylinder because the knock sensor will advance or retard the spark to prevent detonation in every particular driving sequence. There will be no predetonation because the knock sensor will not allow it.
Some engines build up carbon deposits in the combustion chamber. These glow red hot, cause ignition of the fuel before the spark fires, and even those engines are built for 87 AKI the engine needs higher octane to prevent predetonation because of this. It is a carbon problem, not a gasoline problem or knock sensor problem. Spending for higher octane gasoline is a band-aid approach. Cleaning the carbon from the combustion chamber is the right way to deal with this.
A couple of years ago, "Car & Driver" magazine tested several cars on the dyno with different grades of gasoline. They found that engines built for high octane gasoline had power and fuel consumption losses on regular gas that just about evened out the cost savings. Engines built for regular gas had no power improvement on high octane gasoline within the error range of the instruments on the dyno.
Ken
My thought is to always use the lowest octane that will not retard the timing. Knock sensors are like servos. They go right by going wrong. I prefer it not to go wrong first and be right in the outset. I don't think Terry ever said to use lower than optimum octane.
JHZR2
Staff member
terry is right.
In reality, a lot of cars do not have knock sensors. The timing is set pretty much where it will be regardless of octane. And, if the system retards timing, it either retards it just enough to fully combust the fuel, or it retards it to an 86/87 octane level, then slowly increases it back up until knocking is heard again, to constantly maximize advance.
Using a higher octane (more resistant to combustion) fuel in an engine that is designed to take a lower octane fuel will result in higher hydrocarbon levels continuing through the system, eventually being catalyzed and spat out as extra HC and CO2.
In cars with knock sensors, the computer will advance the spark as much as it can, through the point that the engine begins to knock. Then it backs off slightly. This allows use of a higher octane fuel, and better power production. Cars can only take advantage of this so much, though, for example my saab has an extremely modern engine control system, but is designed to take advantage of 90 octane fuel. Beyond that, the spark can't advance, so it is more or less a waste.
Most premium fuels do not contain anymore additives than regular fuels. Although amoco has extra refining steps taken, only shell v-power has extra adds, to the best of my knowledge.
JMH
In reality, a lot of cars do not have knock sensors. The timing is set pretty much where it will be regardless of octane. And, if the system retards timing, it either retards it just enough to fully combust the fuel, or it retards it to an 86/87 octane level, then slowly increases it back up until knocking is heard again, to constantly maximize advance.
Using a higher octane (more resistant to combustion) fuel in an engine that is designed to take a lower octane fuel will result in higher hydrocarbon levels continuing through the system, eventually being catalyzed and spat out as extra HC and CO2.
In cars with knock sensors, the computer will advance the spark as much as it can, through the point that the engine begins to knock. Then it backs off slightly. This allows use of a higher octane fuel, and better power production. Cars can only take advantage of this so much, though, for example my saab has an extremely modern engine control system, but is designed to take advantage of 90 octane fuel. Beyond that, the spark can't advance, so it is more or less a waste.
Most premium fuels do not contain anymore additives than regular fuels. Although amoco has extra refining steps taken, only shell v-power has extra adds, to the best of my knowledge.
JMH
I'm not so sure I buy the argument that burning higher octane fuels in an engine that's meant for lower octane gas increases HC emission. I'd like to see some objective evidence of that. Were that the case, then there should be some percentage of people that insist on running premium gas all the time that would fail their state-mandated emissions inspections, right? And I don't think that happens much, or you'd see stuff plastered all over an owners manual about it. I do agree with the fact that you should only run a gas with an octane level high enough to prevent timing retard on modern engines, and no more-but the fact is, here in Ohio, we only get 3 grades of gas, and we have to fill up with one of them (too much of a PITA to try to mix at the pump yourself).
As for the function of knock sensors, the fact is, they're NOT designed to deal with CCD-induced knocking. They are, as I think everyone here knows, part of a system to allow the computer to advance the timing as far as possible for max power and fuel efficiency. However, I do know that if your knock sensors are running at MAX RETARD and you're still getting knocking, then there is a small amount of unburned fuel that remains in the cylinder, causing a oil wipe-down effect on the cylinder walls and piston ring lands, simply because the gas liquefies the oil. And that's not good for your engine.
I agree with you guys that CCD are the root of the problem in that situation, and running high-octane gas is just a band-aid for the problem. However, I still think that even if you have a clean engine, if you feel knock retard using regular fuel, then step up a grade-I really do think that doing that is better for your engine.
Then again, it's just my opinion-and, as we all know, opinions are like a**holes-everyone's got one!
Fitz
As for the function of knock sensors, the fact is, they're NOT designed to deal with CCD-induced knocking. They are, as I think everyone here knows, part of a system to allow the computer to advance the timing as far as possible for max power and fuel efficiency. However, I do know that if your knock sensors are running at MAX RETARD and you're still getting knocking, then there is a small amount of unburned fuel that remains in the cylinder, causing a oil wipe-down effect on the cylinder walls and piston ring lands, simply because the gas liquefies the oil. And that's not good for your engine.
I agree with you guys that CCD are the root of the problem in that situation, and running high-octane gas is just a band-aid for the problem. However, I still think that even if you have a clean engine, if you feel knock retard using regular fuel, then step up a grade-I really do think that doing that is better for your engine.
Then again, it's just my opinion-and, as we all know, opinions are like a**holes-everyone's got one!
Fitz
Oh, buy the way-Amoco does, in fact, add much more detergents to its premium gas when compared to its regular gas. I think, if memory serves, it adds 4 times the amount mandated by the federales. Kind of like Shell V-power.
Any little bit helps. Especially here in NE Ohio, where all gas is crap (absolutely no pump inspections in this state-they could be selling us 80 octane gas, and no one would be the wiser).
Fitz
Any little bit helps. Especially here in NE Ohio, where all gas is crap (absolutely no pump inspections in this state-they could be selling us 80 octane gas, and no one would be the wiser).
Fitz
And Ken2-
Just because you have knock sensors does not mean that your engine will not knock. Look at all the people on this board alone that have engines with knock sensors who complain about knocking/pinging who use FuelPower.
Fitz
Just because you have knock sensors does not mean that your engine will not knock. Look at all the people on this board alone that have engines with knock sensors who complain about knocking/pinging who use FuelPower.
Fitz
Knock sensors aren't there to cause the spark to be advanced, they are there to retard the spark when there is knock. They don't do anything unless there is knock problem.
Fitz: You want some decent gas stay away from BP
highest content of alcohol up to 15% and is not
good for fuel injectors. There are two Marathon stations on the west side that pump STRAIGHT GASOLINE. No Alcohol not MTBE No Bull#%&*. Due to the regulations in Ohio gas stations do not need to label the pumps as far as alcohol content.
Anyway the two Marathon stations are Columbia Road in Olmsted Falls and West 137th and Brookpark. You will see a mileage increase on straight gas
highest content of alcohol up to 15% and is not
good for fuel injectors. There are two Marathon stations on the west side that pump STRAIGHT GASOLINE. No Alcohol not MTBE No Bull#%&*. Due to the regulations in Ohio gas stations do not need to label the pumps as far as alcohol content.
Anyway the two Marathon stations are Columbia Road in Olmsted Falls and West 137th and Brookpark. You will see a mileage increase on straight gas
On a recent road trip, I was really low on gas, so I bought 5 gallons of 87 octane BP to tide me over to the next Chevron. I filled up with Chevron later that day, so I had about a 25-30% concentration of BP. That tank, and the next tank were 2-3 mpg lower than I expected. The first tank was all highway miles, and I got mileage that I would expect for all city driving! After that BP crap got burned off, mileage went right back to where it was before. And I thought Arco was bad!!!
Guess I better find a new place to buy gas. I have been going to BP for the last 6 months or so, thinking it was decent stuff. Maybe I will try Marathon, as there's one nearby.
I remember a couple of years ago Honda got quite an improvement in HP, crediting "better knock sensors." IIRC it was the accord V6, from 200 to 240hp. This would imply, to me, that the knock sensor is as regular a part of engine control and feedback, as, say, the 02 sensor. In other words, the compression, timing, fueling, etc., of that motor is reliant on having accurate detonation control. I would expect this to be becoming the rule, not the exception. My 92 cutlass ciera, mid-90's saturns have knock sensors; I expect the newest generations to have substantial improvements in efficiency and versatility WRT fuel quality.
Hey Bubba-
Thanks for the info. The Marathon on Brookpark isn't too far from me-I'll try the premium from there and see if my mileage improves.
Go figure that Ohio is only one of 4 states that doesn't test fuel quality.
Fitz
Thanks for the info. The Marathon on Brookpark isn't too far from me-I'll try the premium from there and see if my mileage improves.
Go figure that Ohio is only one of 4 states that doesn't test fuel quality.
Fitz
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