Certainly no harm in running higher octane fuel, but you are most likely wasting your money if you do. Some vehicles take advantage of the higher octane fuel, but most do not. Run Top Tier fuel and you'll stay clean enough.
using higher than minimum octane requirement OK?
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My car runs on regular unleaded gas (love the name RUG).
I drive conservatively.
When I go north to the mountains I "fill 'er up" with high test.
I figure I'm running the engine hotter when I'm zipping round hills and mountain roads I know.
I also figure my "1,000 mile weekends", timely oil changes and quality fuels keep my engine's inwards clean.
NOTE: Add Techron and the like before a stint of local driving. I'm told the PEA is designed to clean the injector nozzles upon shutdown.
I drive conservatively.
When I go north to the mountains I "fill 'er up" with high test.
I figure I'm running the engine hotter when I'm zipping round hills and mountain roads I know.
I also figure my "1,000 mile weekends", timely oil changes and quality fuels keep my engine's inwards clean.
NOTE: Add Techron and the like before a stint of local driving. I'm told the PEA is designed to clean the injector nozzles upon shutdown.
Originally Posted By: NissanMaxima
Hi all:
My Corolla specifies 87 octane or higher. I like Shell but their highest additive concentration is in their high octane (91 here in Colorado). I wrote to them and they said 87 octane (the next step down here in Colorado) has 50% the additive concentration of the 91. Someone in a recent thread said that higher octane fuels if not required by the engine "dirties up" the engine or something like that. Is there any truth to this? I was considering periodically using the Shell 91 octane in the car purely for the higher detergents.
I don't know what elevation you are at (I'm at about 6250), but as a very general rule, when you start getting up in elevation, you can go with lower octane, which is why Regular is 85, Plus is 87, and Premium is 91 in CO. If you read any Ford manual in the last few years, Ford basically wants you running at least 87, no matter the elevation. I have noticed a lot of people here run 85, and I hear a lot of knocking. Just my unscientific observation. I would run the octane that provides knock free running. If you don't care about the hassle, you are probably better off treating your gas every once and a while with a PEA additive, than going the premium route. Gumout or Redline come to mind.
Now, IMHO, with DI engines, you are adding another variable to the mix, and you need to do some research and figure out what octane you want to run.
Hi all:
My Corolla specifies 87 octane or higher. I like Shell but their highest additive concentration is in their high octane (91 here in Colorado). I wrote to them and they said 87 octane (the next step down here in Colorado) has 50% the additive concentration of the 91. Someone in a recent thread said that higher octane fuels if not required by the engine "dirties up" the engine or something like that. Is there any truth to this? I was considering periodically using the Shell 91 octane in the car purely for the higher detergents.
I don't know what elevation you are at (I'm at about 6250), but as a very general rule, when you start getting up in elevation, you can go with lower octane, which is why Regular is 85, Plus is 87, and Premium is 91 in CO. If you read any Ford manual in the last few years, Ford basically wants you running at least 87, no matter the elevation. I have noticed a lot of people here run 85, and I hear a lot of knocking. Just my unscientific observation. I would run the octane that provides knock free running. If you don't care about the hassle, you are probably better off treating your gas every once and a while with a PEA additive, than going the premium route. Gumout or Redline come to mind.
Now, IMHO, with DI engines, you are adding another variable to the mix, and you need to do some research and figure out what octane you want to run.
wemay
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Originally Posted By: BrocLuno
KISS - the lower the octane, the simpler the formula. If the engine runs well on regular, just do that.
IF you have ping and knock issues, THEN you start to step up the octane ladder ...
^This^
KISS - the lower the octane, the simpler the formula. If the engine runs well on regular, just do that.
IF you have ping and knock issues, THEN you start to step up the octane ladder ...
^This^
Originally Posted By: Alex_V
I find 89 octane to be the best value. 87 is junk - none of my engines (little turbo 4 in the Cruze, 454 in the GMC, Briggs in the garden tractor) run well on it. But between 89 and 91/93 there's less difference (almost none that I've been able to find, in the Cruze) and if you're keeping a good regimen of other maintenance practices any moderately higher level of detergents in premium shouldn't be a make-or-break.
Besides, the price gap between 87 and 89 is never wider than 89 to premium which is sometimes the case.
89 is basically a bit of super mixed with 87. Usually Premium is 30-50 cents more than regular, but 89 is usually 15-25 cents more than regular. Make your own mix, just add a little premium if you feel like it. We have 93 here for super so the difference is about 6 points so in theory 89 should only be about a 1/3 the difference between regular and super but it's usually a 1/2. They only deliver regular and super to the gas station.
I find 89 octane to be the best value. 87 is junk - none of my engines (little turbo 4 in the Cruze, 454 in the GMC, Briggs in the garden tractor) run well on it. But between 89 and 91/93 there's less difference (almost none that I've been able to find, in the Cruze) and if you're keeping a good regimen of other maintenance practices any moderately higher level of detergents in premium shouldn't be a make-or-break.
Besides, the price gap between 87 and 89 is never wider than 89 to premium which is sometimes the case.
89 is basically a bit of super mixed with 87. Usually Premium is 30-50 cents more than regular, but 89 is usually 15-25 cents more than regular. Make your own mix, just add a little premium if you feel like it. We have 93 here for super so the difference is about 6 points so in theory 89 should only be about a 1/3 the difference between regular and super but it's usually a 1/2. They only deliver regular and super to the gas station.
Your engine could run fine on 87. However you could be losing 10 - 20 horsepower. Modern turbo engines are detuned to run on 87 but are programmed to take advantage of higher octane fuel.
A blanket statement that if your engine runs fine on 87 that's all you need is incorrect.
A blanket statement that if your engine runs fine on 87 that's all you need is incorrect.
waiting for ping or knock to dictate your choice of fuel in almost any modern engine may leave you... waiting. Many engine designs and programming will detect knock long before you can hear it and retard the timing accordingly.
Even my sig car built July 05 won't make a sound on 87 yet specs 91. I recommend monitoring the KR values via OBDII or careful testing to be certain if you stray from spec'd fuel...
Even my sig car built July 05 won't make a sound on 87 yet specs 91. I recommend monitoring the KR values via OBDII or careful testing to be certain if you stray from spec'd fuel...
The only vehicle I've ever had that seems to benefit from premium gasoline is the Impala. All the others usually ran WORSE on premium and in some cases dropped MPG.
The only exception was I had a 95 Ford Aerostar with the 4.0 engine. During the summer in hot areas (think desert) and with a full load climbing a hill it would ping a little. One time when this was happening I filled up with 89 and the pinging went away. This was in the Arizona desert - it was 117 that day.
Both of my Ford 4.6 engines seem to do the best on 87 octane.
The only exception was I had a 95 Ford Aerostar with the 4.0 engine. During the summer in hot areas (think desert) and with a full load climbing a hill it would ping a little. One time when this was happening I filled up with 89 and the pinging went away. This was in the Arizona desert - it was 117 that day.
Both of my Ford 4.6 engines seem to do the best on 87 octane.
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The higher octane may give better torque that improve driveability,however the effect may not be pronounced on cvt or auto gearbox. If you run manual transmission, and the ECM is programmed to make use of it, definitely there is a noticeable difference. It is just that whether the little difference matter for most people, probably not except for car enthusiast that loves to drive.
I think premium 'carbons up' an engine if you are always putt putting around. 87 is probably ideal if you and your engine are scared of rpms. 89 I think is for old vehicles with alot of miles that were kept running.
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