I'm done with low octane fuel

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I went to fill up my 2.5 gallon gas can for the weedeater with 91 octane. Instead of shutting off the pump and switching over to 87 for the car, I just left it on 91 and went ahead and filled up the car. Stihl recommends 91 or higher octane for their weedeaters. The engine feels like it has 50 more horsepower with the 91. How is that possible you say ? The only thing I can think of is that the knock sensor was retarding the timing with 87 the whole time and I never knew it. I mean it's not a night and day difference, but it's definitely noticeable. And besides that, fuel mileage is up 0.7 mpg. The engine is a 2000 Buick 3800 V6. Fuel is from Costco.
 
I've always run high octane in whatever I drive. Vehicle ran better ,better gas mileage overall ,never a problem running hi test gas in anything
 
I often run higher octane fuel, 95 RON / 85 MON / 90 AKI as according to the owners manual I get a 2.2% increase in power and a 3% increase in torque, it's not much but you can feel it and the tank seems to last longer.

My car has what they call "selective knock control".

Here the regular stuff is 91 RON / 82 MON / 87 AKI
 
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I noticed that as well, but in a car that didn't require anything above regular 87.

I assumed it was because Shell V-Power 91 octane is pretty much the only ethanol free gasoline available in the part of Canada I spend part of the year in.
 
Both cars in my signature specify 91 octane which is rare to find where I live so I use the commonly found 93 octane in everything, even in my stand-on mower.
 
Originally Posted by skyactiv
Both cars in my signature specify 91 octane which is rare to find where I live so I use the commonly found 93 octane in everything, even in my stand-on mower.


In my area we have 87, 89, and 93. Not a big jump on the low end but quite the difference on the high end. I run 93 in the A4, as it calls for 91 and I run 93 in the Civic to try and help with fuel dilution, dont know that it matters but it is a 1.5T so I figured it may help with lspi also. All my other vehicles and the company work van I run 87 as I cant see a difference. Top tier in all regardless of vehicle.
 
dbias
I think you have hit on something. You said, " it may help with LSPI also." I think that high octane gas is better at combatting LSPI than engine oils with a Dexos or SN+ labeling.
 
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I went the other way
smile.gif


I moved from premium (91) to regular(87) on Nissan VQ30DE with 10:1 compression.
Indeed the performance at high RPM is better with 91.But I would notice it only because I know the car very well. MPG is basically the same within 5% - I did not bother to measure it more precisely because it is much lower than the 30-38% price difference of the premium gas here. The price difference used to be lower between the 87 and 91, but now it is in the $0.70-0.90 range.

Turns out for this specific engine the 91 is "recommended" - not "required", so it can leave with 87. If you do the math with 15k mi annually and this engine - it is $50/month difference.
Actually that's my wife's ride and she is not a spirited driver, so I'll take the $50 instead
grin.gif
 
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Anything over 87 octane is a complete waste for most motorists. It is nothing more then a placebo effort that your vehicle has more power. I mistakenly put in 93 octane in my Tahoe while on a cross country trip. I got no more power and the exact same gas mileage as 87 octane. My buddy has 2015 Escalade with the 6.2. The Escalade runs perfectly on 87 octane for the past 90K miles.
 
Originally Posted by MParr
dbias
I think you have hit on something. You said, " it may help with LSPI also." I think that high octane gas is better at combatting LSPI than engine oils with a Dexos or SN+ labeling.


That's what I think also as the higher the octane the harder it is to ignite so it may not ignite off of a small piece of carbon jumping off of the piston. I do notice a slight increase in mpg so it's not all bad.
 
I've been using mostly 88 octane E15 in my GTI for 25k miles now. I tried 91E0 and measured and felt no difference. In the 693 gallons used since May of last year, I've saved about $350...that's going toward a better set of tires.

Much more performance improvement than 10hp.
 
Everything but the DR650 and VStar 250 in my signature runs on 91 or higher. I think the DR650 would run on just about any flammable liquid.
 
Our 2006 Lacrosse 3.8l seems to get 1 - 3 MPG better , in town , with the premium E10 . 19 - 20.5 MPG .

I am pretty sure that it is due to the electronics changing engine timing .

Can not really say it has more power . I am an old man and try to drive to make the gas " go further " .
 
Originally Posted by Tahoe4Life
Anything over 87 octane is a complete waste for most motorists. It is nothing more then a placebo effort that your vehicle has more power. I mistakenly put in 93 octane in my Tahoe while on a cross country trip. I got no more power and the exact same gas mileage as 87 octane. My buddy has 2015 Escalade with the 6.2. The Escalade runs perfectly on 87 octane for the past 90K miles.


So not true! Just because your hunk of GM junk doesn't have smart enough knock control and timing advance based on knock input and other variables doesn't mean MANY other cars on the road don't. I have used 89/91 octane in many vehicles that required the use of 87 and found much better performance backed up by a nice boost in mileage.

ANY of the newer, turbocharged cars on the road today can and will benefit from the use of high octane fuels, that is fact. Sure the manual says you can run 87 in it but that is making the knock controls reduce timing everywhere, ultimately causing lower MPG and poor performance.
 
I have 2 F150 Ecoboost trucks. 2.7L and 3.5L. Both respond well to high octane fuel, with higher MPG and noticeably more pleasant performance. Because they are company trucks I drive them at exactly the speed limit and do not beat on them. I'm not getting a ticket while on the clock! Even so, it's clear that on ramp acceleration is silky smooth with 93 and herky-jerky with 87.

My tuned 5.4L clearly pings on anything other than 93.
 
Originally Posted by DzoG20
I went the other way
smile.gif


I moved from premium (91) to regular(87) on Nissan VQ30DE with 10:1 compression.
Indeed the performance at high RPM is better with 91.But I would notice it only because I know the car very well. MPG is basically the same within 5% - I did not bother to measure it more precisely because it is much lower than the 30-38% price difference of the premium gas here. The price difference used to be lower between the 87 and 91, but now it is in the $0.70-0.90 range.

Turns out for this specific engine the 91 is "recommended" - not "required", so it can leave with 87. If you do the math with 15k mi annually and this engine - it is $50/month difference.
Actually that's my wife's ride and she is not a spirited driver, so I'll take the $50 instead
grin.gif


In my Maxima, the better mpg tanks have been 87. That is based on my regular driving, I did not even attempt to control variables.
 
My FX4 EB does much better on the 91 octane gas. Not only more torque but because of the torque increase the trans shifting schedule seems somewhat different - downshifts more on 87. Of course low rpm high torque situations can propagate LSPI but AFAIK I haven't had that with the engine doing fine @126k. I'm not even using a SN+ oil either; Castrol 0w40 I'm sure doesn't meet any SN+ or Dex2 specs. Not a big fan of 87 gas.
 
I have never run anything other than 87 in my DI Hyundai and have no plans to. The car doesn't knock on 87.

At the gas station down the street from my office, 93 is 50 cents a gallon more than 87. In my usage profile I get about 28mpg in mixed freeway/city/stop and go driving, and about 450 miles a tank, at the current 87 price of $1.99, a tank is $31.98 (450/28*1.99)

The breakeven on better mileage with 93 would be a little north of 35mpg (450/35*2.49) is $32.01 rounded to the nearest hundredth. I can't see this car instantly getting 7mpg better just by giving it more octane.

Maybe it would subjectively "feel" smoother or faster. If BITOG users would like to send me money to conduct this experiment, then I would be happy to run 93 until the subsidy expired, and report back my findings. Otherwise, I'm sticking with 87.

I will say, you know something that did make it feel smoother and faster, is changing out the OEM spark plugs. I didn't get to 100K but they were pushing 7 years old, so I changed them out. That made a difference in the seat of my pants. Of course YMMV.
 
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