Awhile back I bought a new Pathfinder and a buddy had a newer truck. He told me I should use a higher octane gas instead of the recommended 87. Do people really think it is cleaner or better just because it is more expensive? A person would just be better off going to a newer name brand gas station that maintains their facility very well.
People think using higher octane gas is better?
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This has been beaten to death here. Use the search function.
It has been beaten but I will say 1% or under of the population has no clue what octane is and how to take advantage of the numbers. Don't even get me started with cetane.
It depends on the engine and engine computer programming. Some engines are detuned to run on 87 and make more power/get better fuel economy on higher octane, while others don't see any benefit.
Originally Posted By: stygz
Do people really think it is cleaner or better just because it is more expensive?
Not me. I have owned 3 Lexus vehicles that all call for 91 octane. In an accumulated 430,000 miles (so far) none have had anything but tier one 87 octane. Each have gotten a Techron or Regane fuels system additive every 20,000 miles and new air filter every 20,000 (Fram). All were tuned up with new spark plugs once at 120-140,000 miles and the throttle body cleaned.
The results: Zero pinging. 28-32mpg. clean TB.
The experiment continues.
FWIW the engines 2- 3.5L and one 3.3L V6 all run on 5w30 syn oil OCI 5000
Do people really think it is cleaner or better just because it is more expensive?
Not me. I have owned 3 Lexus vehicles that all call for 91 octane. In an accumulated 430,000 miles (so far) none have had anything but tier one 87 octane. Each have gotten a Techron or Regane fuels system additive every 20,000 miles and new air filter every 20,000 (Fram). All were tuned up with new spark plugs once at 120-140,000 miles and the throttle body cleaned.
The results: Zero pinging. 28-32mpg. clean TB.
The experiment continues.
FWIW the engines 2- 3.5L and one 3.3L V6 all run on 5w30 syn oil OCI 5000
Although Ford says you can run 87 octane fuel in the 3.5 Ecoboost engine, owners including myself might want to consider running a higher octane fuel because of low speed pre ignition (LSPI). Soot in the oil is an issue as well.
Interesting read here: www.gf-6.com
Check out the article about turbo gas direct injected engines.
Interesting read here: www.gf-6.com
Check out the article about turbo gas direct injected engines.
My saturn econobox owners manual said if it was over 90'F it'd run better on high test.
Knock sensors have moved from an emergency "uh oh" safety valve for turbos to a normal part of the engine feedback system. If you put higher test it, it might just use it.
Knock sensors have moved from an emergency "uh oh" safety valve for turbos to a normal part of the engine feedback system. If you put higher test it, it might just use it.
I use 'premium' octane blends in my engines that require them.
It's only to minimize/preclude detonation that would otherwise occur consuming low(er) octane formulations. There's no other rationale imho.
It's only to minimize/preclude detonation that would otherwise occur consuming low(er) octane formulations. There's no other rationale imho.
Originally Posted By: Doog
Not me. I have owned 3 Lexus vehicles that all call for 91 octane. In an accumulated 430,000 miles (so far) none have had anything but tier one 87 octane. Each have gotten a Techron or Regane fuels system additive every 20,000 miles and new air filter every 20,000 (Fram). All were tuned up with new spark plugs once at 120-140,000 miles and the throttle body cleaned.
The results: Zero pinging. 28-32mpg. clean TB.
I had an interesting discussion on the Lexus forum regarding this. I have run 85 octane (equivalent to 87 at lower elevations) with an occasional Techron in our 2004 Lexus RX330 since new. The owner's manual says 87 is required but for better performance use 91.
One poster said I would ruin the catalytic converter, I only can run it because I am in Colorado at higher elevation, another said engine damage would occur, another said better cleaning with high octane, some said "they could feel the difference with a fill-up of 91", etc .... just went over 195,000 trouble-free miles.
Not me. I have owned 3 Lexus vehicles that all call for 91 octane. In an accumulated 430,000 miles (so far) none have had anything but tier one 87 octane. Each have gotten a Techron or Regane fuels system additive every 20,000 miles and new air filter every 20,000 (Fram). All were tuned up with new spark plugs once at 120-140,000 miles and the throttle body cleaned.
The results: Zero pinging. 28-32mpg. clean TB.
I had an interesting discussion on the Lexus forum regarding this. I have run 85 octane (equivalent to 87 at lower elevations) with an occasional Techron in our 2004 Lexus RX330 since new. The owner's manual says 87 is required but for better performance use 91.
One poster said I would ruin the catalytic converter, I only can run it because I am in Colorado at higher elevation, another said engine damage would occur, another said better cleaning with high octane, some said "they could feel the difference with a fill-up of 91", etc .... just went over 195,000 trouble-free miles.
Originally Posted By: stygz
Awhile back I bought a new Pathfinder and a buddy had a newer truck. He told me I should use a higher octane gas instead of the recommended 87. Do people really think it is cleaner or better just because it is more expensive?
Did your buddy say WHY he thinks you should use higher octane?
Most people who don't understand octane probably see gas grades according to the "good-better-best" marketing formula. If you want the "best" for your baby, you'll spend a little more for premium/super/ultra/gold or whatever.
I will say that my '01 5.3 Chevy has better low-end response and pings less on higher octane (and Torque shows progressively less knock retard with 89 and 93 vs. 87). On 87, it hammers like a diesel when I lay on the gas and always has, even with a steady diet of cleaners like Techron, Regane, and Fuel Power. My solution is to use 87 and keep my foot out of it.
Awhile back I bought a new Pathfinder and a buddy had a newer truck. He told me I should use a higher octane gas instead of the recommended 87. Do people really think it is cleaner or better just because it is more expensive?
Did your buddy say WHY he thinks you should use higher octane?
Most people who don't understand octane probably see gas grades according to the "good-better-best" marketing formula. If you want the "best" for your baby, you'll spend a little more for premium/super/ultra/gold or whatever.
I will say that my '01 5.3 Chevy has better low-end response and pings less on higher octane (and Torque shows progressively less knock retard with 89 and 93 vs. 87). On 87, it hammers like a diesel when I lay on the gas and always has, even with a steady diet of cleaners like Techron, Regane, and Fuel Power. My solution is to use 87 and keep my foot out of it.
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A further thought, some of the high octane here is ethanol free which would be a benefit besides the octane improvement
This is one of those topics that will most likely never garner factual/definitive answers. Seems like the butt dyno rules. (It feels more powerful.)
The octane issue has been discussed ad nauseam related to my car, Mazda3 Skyactiv. My average fuel economy over several tanks of top tier premium did not change significantly. I consider any change less than 1 mpg to be due to normal distribution and not significant. I cannot address the fuel dilution topic, nor do I care about said topic.
I think the best plan is to use whatever you want and stop looking for validation from opinionated folks.
The octane issue has been discussed ad nauseam related to my car, Mazda3 Skyactiv. My average fuel economy over several tanks of top tier premium did not change significantly. I consider any change less than 1 mpg to be due to normal distribution and not significant. I cannot address the fuel dilution topic, nor do I care about said topic.
I think the best plan is to use whatever you want and stop looking for validation from opinionated folks.
you live in higher elevation, and for that, standard 87 octane (Ron+Mon divide by 2) gets lowered to 85 due to higher elevations.
higher octane rating gasoline is designed for engine(s) that has the following characteristics:
(1) combustion chamber has a lot of deposits that (a) raise the compression ratio; (b) these deposits "glow" like glow plugs during operation,
(2) engine(s) that is designed with high compression ratio to begin with, and the entire design revolves around higher octane gasoline (e.g. 91 octane).
For (1), unless your engine is carb'ed and running rich/poorly for quite some time (cold/open thermostat, amongst a few other things), this is very unlikely these days.
For (2), this is quite a norm for higher performance engines. Many prestige brands of automobiles are designed to run on 91 octane gasoline.
Because of computer engine management and ignition mapping, most engines spec'ed to run on 91 octane gas can tolerate 89 or lower gasoline for some time (basically shift by retardation the ignition mapping based on the knocking received while engine in operation).
Also: regardless of what octane of gasoline used: a properly functioning gasoline engine should be capable of combusting the fuel-air mixture properly, and the exhaust will still go through the cat convertor, regardless of octane.
Remember: octane rating (the "anti-knock" capability of gasoline) is meant when the 4 cycle IC engine is up in compression mode, right up to, but before the spark flies. Anything that soon after the spark flies shall ignite the fuel-air mixture and burn the mix completely, and any additives, etc. in the mix should now become spent and gets passed out the exhaust system as "exhaust gas".
those who claimed that running "91" will ruin cat con should go back to take some fundamental automotive courses.
Q.
higher octane rating gasoline is designed for engine(s) that has the following characteristics:
(1) combustion chamber has a lot of deposits that (a) raise the compression ratio; (b) these deposits "glow" like glow plugs during operation,
(2) engine(s) that is designed with high compression ratio to begin with, and the entire design revolves around higher octane gasoline (e.g. 91 octane).
For (1), unless your engine is carb'ed and running rich/poorly for quite some time (cold/open thermostat, amongst a few other things), this is very unlikely these days.
For (2), this is quite a norm for higher performance engines. Many prestige brands of automobiles are designed to run on 91 octane gasoline.
Because of computer engine management and ignition mapping, most engines spec'ed to run on 91 octane gas can tolerate 89 or lower gasoline for some time (basically shift by retardation the ignition mapping based on the knocking received while engine in operation).
Also: regardless of what octane of gasoline used: a properly functioning gasoline engine should be capable of combusting the fuel-air mixture properly, and the exhaust will still go through the cat convertor, regardless of octane.
Remember: octane rating (the "anti-knock" capability of gasoline) is meant when the 4 cycle IC engine is up in compression mode, right up to, but before the spark flies. Anything that soon after the spark flies shall ignite the fuel-air mixture and burn the mix completely, and any additives, etc. in the mix should now become spent and gets passed out the exhaust system as "exhaust gas".
those who claimed that running "91" will ruin cat con should go back to take some fundamental automotive courses.
Q.
Quest, what about the claims, related to the Skyactiv engines, that the engine "detunes itself" to allow it to run on 87 octane, but using higher octane will result in magic?
I'm not buying into it for the simple fact that U.S. spec Skyactive engines are built with lower compression ratio than the Japan/Europe spec engines that require the higher AKI fuel.
I'm not buying into it for the simple fact that U.S. spec Skyactive engines are built with lower compression ratio than the Japan/Europe spec engines that require the higher AKI fuel.
What compression ratio is your Skyactiv engine runs on? (sorry, not familiar with these skyactiv engines...for I'm an old-fashioned Mazda guy spending most of my time in their rotary/B series block days)?
My fit came with compression ratio of around 10.5:1, and spec'ed to run on 87 octane gas.
I occasionally run 91 mix (whatever 87I have left in my tank) and the engine feel a bit snappier, but otherwise for the most part: fuel-economy remains pretty much the same as before. It's just that when I turn on the A/C compressor during summer time, running a mix higher than 87 octane rating will reduce the "snap"--drag sensation (when A/C kicks in) and the car accelerates smoother.
Newer fit runs on 11.5:1 compression ratio, and yet still spec'ed to run on 87 octane rating gasoline. Detuned? perhaps so, but so long as it supports bare minimum of 87 octane rating gasoline (R+M/2), that that should be ok.
In your case my perception of skyactiv engine designs has to do with improving mechanical efficiency/reduction of frictions to improve fuel economy. Given all other things being equal (somewhat similar compression ratio to that of most Honda iVTEC engines nowadays, which hovers around 11:1 or more), then it wouldn't be at all, surprised that what you feel about (magic) maybe similar to mine?
Lastly: ignition mapping is not as difficult to understand as many people think:
Remember this: with gasoline engines on OBD-II design now runs on individual over-the-plug top coil configuration (can control individual cylinder ignition timing and mapping), and pretty much all of them comes with a knock sensor on the block as a feedback mechanism back to the ECU, typical engine ignition mapping is designed to dynamically run the ignition timing to just before the 1st sense of "preignition" knock is being sensed. Given the higher octane rating gasoline resists knocks better than 87, and given the ignition timing is dynamically "Read" and actively adjusted, it is of no surprise that by using higher octane gasoline (resists preignition better) the ignition timing will advance a bit further than that of 87, but again, it will stay within the "Safe" zone where the just-before-knocking sound is being picked up by the knock sensor.
Even newer, all computer controlled german diesel engines are like that nowadays, with adjustable diesel pumps and knock sensor to constantly read and adjust the spray timing and duration to minimise that dreaded "clacking" sound and gives better power output and exhaust control.
My understanding...
Q.
My fit came with compression ratio of around 10.5:1, and spec'ed to run on 87 octane gas.
I occasionally run 91 mix (whatever 87I have left in my tank) and the engine feel a bit snappier, but otherwise for the most part: fuel-economy remains pretty much the same as before. It's just that when I turn on the A/C compressor during summer time, running a mix higher than 87 octane rating will reduce the "snap"--drag sensation (when A/C kicks in) and the car accelerates smoother.
Newer fit runs on 11.5:1 compression ratio, and yet still spec'ed to run on 87 octane rating gasoline. Detuned? perhaps so, but so long as it supports bare minimum of 87 octane rating gasoline (R+M/2), that that should be ok.
In your case my perception of skyactiv engine designs has to do with improving mechanical efficiency/reduction of frictions to improve fuel economy. Given all other things being equal (somewhat similar compression ratio to that of most Honda iVTEC engines nowadays, which hovers around 11:1 or more), then it wouldn't be at all, surprised that what you feel about (magic) maybe similar to mine?
Lastly: ignition mapping is not as difficult to understand as many people think:
Remember this: with gasoline engines on OBD-II design now runs on individual over-the-plug top coil configuration (can control individual cylinder ignition timing and mapping), and pretty much all of them comes with a knock sensor on the block as a feedback mechanism back to the ECU, typical engine ignition mapping is designed to dynamically run the ignition timing to just before the 1st sense of "preignition" knock is being sensed. Given the higher octane rating gasoline resists knocks better than 87, and given the ignition timing is dynamically "Read" and actively adjusted, it is of no surprise that by using higher octane gasoline (resists preignition better) the ignition timing will advance a bit further than that of 87, but again, it will stay within the "Safe" zone where the just-before-knocking sound is being picked up by the knock sensor.
Even newer, all computer controlled german diesel engines are like that nowadays, with adjustable diesel pumps and knock sensor to constantly read and adjust the spray timing and duration to minimise that dreaded "clacking" sound and gives better power output and exhaust control.
My understanding...
Q.
Originally Posted By: DBMaster
Quest, what about the claims, related to the Skyactiv engines, that the engine "detunes itself" to allow it to run on 87 octane, but using higher octane will result in magic?
I'm not buying into it for the simple fact that U.S. spec Skyactive engines are built with lower compression ratio than the Japan/Europe spec engines that require the higher AKI fuel.
The knock sensors simply convey to the ECU that the engine is knocking, and the RCU retards the timing until it stops.
Quest, what about the claims, related to the Skyactiv engines, that the engine "detunes itself" to allow it to run on 87 octane, but using higher octane will result in magic?
I'm not buying into it for the simple fact that U.S. spec Skyactive engines are built with lower compression ratio than the Japan/Europe spec engines that require the higher AKI fuel.
The knock sensors simply convey to the ECU that the engine is knocking, and the RCU retards the timing until it stops.
I often buy the premium for my car Grand Marquis as it has pinging on lower octane and the premium does not have ethanol added to it at a certain gas station. On the highway I generally use regular though. My Montero says premium recommended but I cannot tell any difference in performance or fuel economy.
So, being a novice on this, I ask... In winter when the fuel ignites less easily due to colds temps...would it actually bet BETTER to run 87 octane to make it easier to ignite? I might ask this in a separate thread if this is off the threads line.
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