Higher octane than recommended a waste?

[zeng]

Originally Posted By: PeterPolyol
On one hand, you have debunkers, skeptics and experts telling us using a higher octane/AKI fuel than the minimum sanctioned in the User Guide literature is of zero benefit, so don't waste your money. OTOH there are plenty of 'lay people' and 'non-experts' saying they've noticed a improvement in torque and response (and sometimes smoothness).

Naturally, certain people will simply add the latter group to the long list of "dumb people that are always falling for illusion and self-suggestion".

Given that, what do you believe and why?

I believe most or all people above are talking sense and 'right' in their own way ......
for each is encountering a specific body-part of an elephant as in a trunk, ears , nose etc in relating one's experience or judgement.
The resultant effects of upgrading to a higher RON fuels varies and are situation-specific from vehicles to vehicles.
Just my 2 cents.

 

[555]

What's going on here? Just two pages!?
A little disappointed that throttle response doesn't get mentioned a little more, specifically on a hot day with the a/c on high in stop and go traffic.
Each vehicle is different.
I chauffeur the dog to various places in a Subaru CrossTrek CVT that gets a steady diet of 87 octane. On hot (92+ degrees F)and humid days with the a/c on high(a mix of recirculate and non) the throttle response feels like turbo lag. From a red light the response is the same whether I feather the throttle, floor it, or somewhere in between.Recently the tank was close to empty, so I threw some 93 octane in there. Throttle response improved noticeably, I got something more when I pressed on the throttle as opposed to the homogenized response I got on 87 octane. Better mileage? Maybe, but I get good mileage anyways and I enjoy throttle response better than a bumper car. Don't need an entire tank of 93 octane, but in the summer a few gallons here and there doesn't hurt that much at the pump.
Direct Injection engines require less octane, but again depends on the vehicle if you will benefit from higher octane. The word "benefit" could be defined differently by different drivers. Fuel savings? Throttle response? Peace of mind(perceived or imagined)?
Driving style makes a difference too. What do you want when you drive?
More questions than answers.
Vehicle, conditions, driving style. There's a flow chart in there for someone who is interested enough.

 

[4WD]

The test of conviction will come when regular is $4 and premium is $5 in a 20 gallon tank.
Not a big "decide" at current prices ...

 

[Shannow]

Originally Posted By: 4WD
The test of conviction will come when regular is $4 and premium is $5 in a 20 gallon tank.
Not a big "decide" at current prices ...


Caprice at 16MPG US, and $1.45/L (Oz) got it replaced with Captiva Diesel with 26MPG US and $1.19/L Oz...

 

[4WD]

Good point - I'm seeing the roads and car lots packed with bigger trucks and SUV's again - but with a decent mix of higher MPG CUV/sedans. I have quiet fun seeing the young guys with a middle of the road job buy these $60k trucks as the daily driver - some have not been around long enough to see how fast oil prices can change - we'll see ...

My "conviction" to hold my fleet a long time will come when we get that Ford Ranger diesel 4WD you guys get.
(Rode in some in South Africa/Namibia) ...

 

[Silk]

My Volvo is supposed to have a premium fuel, that would be 95 here, but run it on 91 - with a knock sensor it will remap the ignition curve. When travelling to the city I put fuel in at an unmaned station, it has 98 for the same price as 91 in town. Certainly it gets better economy on the open road, but no better around town. 90% of the time it's on 91.

 

[bbhero]

Really good post 4wd. I think that you are right on with your thinking here. Too many people with memories short has their pinky finger out here don't realize just how fast gas prices can go up. I distinctly remember when my step father told me in 2001 that gas prices were going to head up by the next year. Gas was $1.29 for regular and $1.49 for 93 at the time. A yr later regular was $2.29 and 93 was $2.49. So, yeah it can change in a hurry. I remember in 2007-08 when regular was over $4 a gallon and thinking to myself how much is cost to fill up a honking vehicle like a Ford Excursion. A lot of people got their rear ends handed to them when gas got over $4 a gallon.

 

[Shannow]

Originally Posted By: 4WD
My "conviction" to hold my fleet a long time will come when we get that Ford Ranger diesel 4WD you guys get.
(Rode in some in South Africa/Namibia) ...


For the record, my baby Duramax Colorado is getting 26MPG too, loving it.

 

[Vern_in_IL]

got a 2.6L 4cyl Nissan NA motor. I can eek out another 1-2 mpg with premium in the summer months only. Not worth the cost.... and BTW the "original" V-Power does increase MPG slightly.


You really can't go by octane anymore, especially when the gas is not top tier. Various levels of detergents and additives in various grades, and you got that ethanol, and that % varies all the time (UP TO 10%)(and absorbs water)

Makes me wonder how consistent the chemical makeup of gas(OHOL) really is! I want gasoline... not spiked 85 octane!

DOES IT HAVE TO BE THIS COMPLICATED? In the old days you got gas because of the Dinosaur on the sign, or it was convenient, now it's like a frigging ingredients list on a diet Coke.

 

[circuitsmith]

Originally Posted By: 555
Recently the tank was close to empty, so I threw some 93 octane in there. Throttle response improved noticeably, I got something more when I pressed on the throttle as opposed to the homogenized response I got on 87 octane. Better mileage? Maybe


I got the same result with my Matrix in 90F+ weather.
No improvement in mileage, so I only did it once as a test.
That was in mostly stop-and-go traffic, so I plan to try again next time I'm on a long road trip in hot weather.

 

[ls1mike]

Originally Posted By: Vern_in_IL
got a 2.6L 4cyl Nissan NA motor. I can eek out another 1-2 mpg with premium in the summer months only. Not worth the cost.... and BTW the "original" V-Power does increase MPG slightly.


You really can't go by octane anymore, especially when the gas is not top tier. Various levels of detergents and additives in various grades, and you got that ethanol, and that % varies all the time (UP TO 10%)(and absorbs water)

Makes me wonder how consistent the chemical makeup of gas(OHOL) really is! I want gasoline... not spiked 85 octane!

DOES IT HAVE TO BE THIS COMPLICATED? In the old days you got gas because of the Dinosaur on the sign, or it was convenient, now it's like a frigging ingredients list on a diet Coke.


There is that too. That is why I said you can't go off of feel. HP tuners is great tool for watching timing.

There is a difference between what brand of gas too, even if it is the same octane. I don't know how consistent it is between brands, but what I have noticed is the Chevron I use locally is petty consistent.

I also use Fred Meyer premium in my The WS6, Truck and Caprice and it pull timing out at WOT as compared to the Chevron, but I get a really good gas discount there and the fuel there is fairly consistent.

Like I said the only time I can tell without the aid of laptop is when towing.

 

[Olas]

depends why they recommended the grade they did. Lots of engines perform better better on high grade but the owners manual recommends regular because the customer wouldn't buy a car that 'requires' premium.

Anything with a knock sensor doesn't care what fuel you use, but at the same time anything with a knock sensor will perform closer to its intended parameters if it doesn't consistently have to Pull timing.

Anything open loop is more specific, more octane than required is wasteful but protection at the same time - lower than required can be catastrophic.

 

[4WD]

Nice - we need more of the mid size in competition here - too close to full size truck price - it will happen ...

 

[stephen9666]

In my Cruze running higher octane nets me a bump in mileage, sometimes as much as a few MPG.

In the past, the different in price between 87 and 89 was big enough that it negated the MPG gain and the cost per mile was higher. However, the prices between 87 and 89 are closer now than in the past in my area. The Cruze runs like garbage in the heat, so it gets 89 and the mileage gain just about covers the cost.

Going up to 91 is a big jump in price in my area and the gain in mileage is nowhere close to covering the cost, so running 91 isn't worth it.

 

[ls1mike]

Originally Posted By: 4WD
Nice - we need more of the mid size in competition here - too close to full size truck price - it will happen ...

I don't understand.

 

[PeterPolyol]

Interesting experiences and thank you all for sharing.

One thing's clear, it really depends eh? Some of you guys are recording evident results and it seems to be on the modern GDI-T or high-CR NA engines. I know those things are *never* running at full-tune, because they can not only sense IGN timing, but they can customize cylinder-pressure too with the VVT. They say DI alone is good for "1 point of static CR". But then on top of that these new ECU can use the VVT to bleed off cylinder charge, stage multi-injections (inject earlier during intake stroke to cool), modify boost pressure etc. There's no mystery then why we can run 11:1 on a turbo with 87 octane, right? The Intake timing must rarely ever see 0 degrees! No wonder the industry has turned back to using vacuum pumps. Some of you guys even have tools at hand to see the symphony all happening live.

My last octane experiment was on a N/A GM V6 that I thought should not respond at all but was surprised to find some ''hard, scientific'' butt dyno effects. There was what I felt like improved response off the line, but the more obvious effect was sustained low-mid RPM torque. Eg. I could drop it into 3rd doing about 60MPH (4 spd auto), let the trans lock-up in 3rd and inch the pedal down a bit- just to the point before the TCM would unlock it- maybe a 1/4 pedal. WOW. For a quarter-pedal on a GM with a slushy drivetrain, that lockup+full advance is really sweet. You'd get some very nice pull at modest RPMs with no TC slippage. I'd put that accel on par with maybe half throttle, 3rd unlocked (TC slipping away). That was really nice, something I couldn't do on 87 where it would just pull timing, requiring a deeper angle on the pedal and throwing it out of lockup. I never scanned it, but it's quite obvious to me there was a difference.

Seriously, if anyone has a 4 speed GM with an LX9 3500, try it! You'll be surprised at the low-RPM torque you can take advantage of with minimal pedal, locked-up in 3rd

 

[Drew99GT]

On my Corolla, 87 octane in the summer with A/C on makes it ping like marbles in a coffee can. With 91 octane, it's whisper quiet and the engine feels like it has 20 more hp. It also easily gets 2 to 3 more mpg measured with the same weekly driving habits. With current fuel prices, it's a no brainer for me to run premium, especially since it's fairly cheap at the grocery store compared to branded gas stations. In the winter, I run 85 octane without any ping (high altitude/Colorado).

 

[HangFire]

Originally Posted By: Drew99GT
On my Corolla, 87 octane in the summer with A/C on makes it ping like marbles in a coffee can. With 91 octane, it's whisper quiet and the engine feels like it has 20 more hp. It also easily gets 2 to 3 more mpg measured with the same weekly driving habits. With current fuel prices, it's a no brainer for me to run premium, especially since it's fairly cheap at the grocery store compared to branded gas stations. In the winter, I run 85 octane without any ping (high altitude/Colorado).


Yes, lots of variables. My 10th Gen Corolla is fine and happy on 87 Octane E10 Summer or Winter, at relatively low altitude. I never really thought about altitude. Another variable is a heavily carbonized combustion chamber.

But primarily, compression ratio and the ECU's eagerness (or lack thereof) to dial in ignition retard determine whether an engine will be responsive to higher octane or not.

 

[nZone]

I'm the "lay people" or "non-experts".

2000 Infiniti G20t requires 87-octane. Always used Shell/Mobil 93 or sometimes Sunoco 94. Donated in 2014 @ approx. 180,000-mi. The car starts and drives like it was in 2000 (new), and was very peppy. I'm sure the fuel injectors and intake and exhaust valves were super clean.

2006 Honda Odyssey requires 87-octane. Always use Shell 93, and sometimes Mobil 93. Still own, the car starts and drives like it was in 2006 (new), and is very peppy. Like the 2000 Infiniti G20t, I'm sure the fuel injectors and intake valves and exhaust valves were super clean.

2011 Acura MDX ADV requires 91-octane. Always use Shell 93, and a few times used Speedway 93 (formerly Hess 93). Even at the same octane number, Speedway 93 runs like [censored], not smooth or peppy. It's like 1 cylinder is deactivated. On the other hand, Shell 93...vroom vroom.

I don't know any better. I just stick to what works and how I felt about the engine's feedback. Some may say why not use 87-octane and use Chevron cleaner every oil change? Well, do you wash your dishes with soap once a week?

 

[Errtt]

2 of the vehicles (Camry & Tucson) get regular 87. No noticeable pinging so we stick to it. If pinging was there, I'd go up in octane until I figure & fix the cause.
Wife's Lexus RX330 calls for premium so that's what it gets.
All vehicles gets Chevron except maybe a rare occasion here and there.