What's the best octane to use?

[RUFFSTUFF]

The end result of running 87 vs 91+ is neither detremental or beneficial. It is net neutral.

Ignition timing is now net neutral. Interesting.

 

[MisterMac]

Ignition timing is now net neutral. Interesting.

Please stop being obtuse. The computer automatically adjusts timing for the efficient combustion of the fuel across the spectrum of regular through premium.

 

[RUFFSTUFF]

Please stop being obtuse. The computer automatically adjusts timing for the efficient combustion of the fuel across the spectrum of regular through premium.

Ok Professor Mac, does timing affect performance?

 

[MisterMac]

Ok Professor Mac, does timing affect performance?

87 = Performance

91+ = High Performance.

Performance is the action or process of carrying out or accomplishing an action, task, or function.

The Stinger performs as intended on 87.

The Stinger puts out High Performance on 91+.

The lack of high performance is not equal to no performance.

There is your lesson for today.

 

[stung cb]

If you run 87, the ECU will change the calibration to suit. The end result is not beneficial. If paying for Premium fuel is an issue, a Kia Optima 2.0L will run all day on 87... Just a suggestion.

In the 2018 manual, Kia stated matter-of-factly that the car was "designed to use only unleaded fuel having a pump octane number (R+M/2) of 87 (RON 91) or higher." In 2019 and 2020 this was changed to the "recommended" line that you point out. In the very next paragraph it says "Using unleaded gasoline with an octane rating lower than RON 95 [91 R+M/2] could result in loss of engine power and increase in fuel consumption".

So a few of things could have happened. Kia could have made a change to the ECU calibration in 2019 and 2020 that makes 91 more suitable. Maybe in further testing they determined that 91 resulted in better overall performance, economy, and drivability. Most performance vehicles use the "recommended" wording, including my Corvette. At the end of the day, the drives "fine" on regular.

That being said, it's a twin turbo, moderately-high compression V6. I'd certainly feel stupid if the $7 per fill up I saved by not using premium fuel resulted in engine damage from detonation. Even if it didn't, I paid good money for the power the Stinger offers, I'm not sure why I'd run low grade fuel (outside of long highway trips) to save a few pennies but get worse performance and fuel economy.

If

In the 2018 manual, Kia stated matter-of-factly that the car was "designed to use only unleaded fuel having a pump octane number (R+M/2) of 87 (RON 91) or higher." In 2019 and 2020 this was changed to the "recommended" line that you point out. In the very next paragraph it says "Using unleaded gasoline with an octane rating lower than RON 95 [91 R+M/2] could result in loss of engine power and increase in fuel consumption".

So a few of things could have happened. Kia could have made a change to the ECU calibration in 2019 and 2020 that makes 91 more suitable. Maybe in further testing they determined that 91 resulted in better overall performance, economy, and drivability. Most performance vehicles use the "recommended" wording, including my Corvette. At the end of the day, the drives "fine" on regular.

That being said, it's a twin turbo, moderately-high compression V6. I'd certainly feel stupid if the $7 per fill up I saved by not using premium fuel resulted in engine damage from detonation. Even if it didn't, I paid good money for the power the Stinger offers, I'm not sure why I'd run low grade fuel (outside of long highway trips) to save a few pennies but get worse performance and fuel economy.

Hey Pilot Cal.....I respect your opinion bunches. I still feel if burning something less than 91 was going to cause damage to the engine in any shape or form, KIA would distinctly spell it out in the manual and probably a warning notice on the gas cap. So the damage issue (in my opinion) is not an issue. Are there any tests with confirmed facts as to how much performance loss there is by not using 91 octane? Or is it just matter of opinion. Am I going to lose .1, .2 or .3 seconds off the 4.7 advertised 0-60?
It would be interesting to know (in my opinion) what I'm losing/ gaining for the extra $7 per fill up.

 

[Kyle_Gates]

Well, so far I have run 91 (in Denver). No issues, no complaints (granted, I am also a stock Stinger though which.....I think i saw 1 other forum member who was stock once, a LONG time ago, it was like spotting a live dinosaur!!). At 300-400 miles a month, not like the price diff will break the bank (I have my children for that).

 

[stung cb]

87 = Performance

91+ = High Performance.

Performance is the action or process of carrying out or accomplishing an action, task, or function.

The Stinger performs as intended on 87.

The Stinger puts out High Performance on 91+.

The lack of high performance is not equal to no performance.

There is your lesson for today.

Thank you MisterMac. I totally agree.

 

[stung cb]

Well, so far I have run 91 (in Denver). No issues, no complaints (granted, I am also a stock Stinger though which.....I think i saw 1 other forum member who was stock once, a LONG time ago, it was like spotting a live dinosaur!!). At 300-400 miles a month, not like the price diff will break the bank (I have my children for that).

Hey Kyle Gates. I live just west of you in a Denver burb with a two week new 2020 GT2 AWD Silver/Black and I plan on keeping it pure stock except for a full frontal clear bra. What have you?

 

[SafetyPilotCal]

If

Hey Pilot Cal.....I respect your opinion bunches. I still feel if burning something less than 91 was going to cause damage to the engine in any shape or form, KIA would distinctly spell it out in the manual and probably a warning notice on the gas cap. So the damage issue (in my opinion) is not an issue. Are there any tests with confirmed facts as to how much performance loss there is by not using 91 octane? Or is it just matter of opinion. Am I going to lose .1, .2 or .3 seconds off the 4.7 advertised 0-60?
It would be interesting to know (in my opinion) what I'm losing/ gaining for the extra $7 per fill up.

On a stock vehicle, it /shouldn't/ cause damage. Otherwise, as you state, Kia would have used more explicit language in the manual. I'm unable to provide you with any raw data on performance loss since I've never done any tests. Not being well versed in the nuances of the SIM2K ECU our cars have, I cannot truthfully tell you exactly what happens. Anecdotally though, I've dabbled enough in tuning, including an E85 conversion and heavier mods on my SC 3800 Regal, to say that octane absolutely plays a huge role in being able to ramp up timing before encountering knock.

Our ECU is significantly smarter than the rutabaga running my Regal, so maybe it can do all sorts of gee-whiz stuff when it detects knock, especially with control over the cam position. But that being said, if the car put out optimum performance at 87, Kia would have just printed that in the manual. There has to be some reason they outlined performance and fuel economy could be reduced. And I also admit I come from a far different world where turbocharging/supercharging was a bit more exotic and always required premium fuel. So for those reasons, I personally will continue to use 91+ octane. If 87 works for your driving style, the manual doesn't say not to run it, so you're probably fine.

 

[RUFFSTUFF]

87 = Performance

91+ = High Performance.

Performance is the action or process of carrying out or accomplishing an action, task, or function.

The Stinger performs as intended on 87.

The Stinger puts out High Performance on 91+.

The lack of high performance is not equal to no performance.

There is your lesson for today.

Hope you offer refunds on your class because only an idiot would try to sell that 87 octane gives you "as intended" performance but running 91+ gives you "high" performance.

Please step away from the keyboard.

 

[turboAWD]

How do you guys get $7 per fill? Let's say 14 gallons - is 91 octane $0.50 more per gallon where you're at? Around here (CA) we get 87, 89 is usually 87 + $0.10 and 91 is 87 + $0.20. So the extra cost for filling up with 91 vs. 87 is like $3.00 for a full tank.

 

[MisterMac]

Hope you offer refunds on your class because only an idiot would try to sell that 87 octane gives you "as intended" performance but running 91+ gives you "high" performance.

Please step away from the keyboard.

What is this? High school? You should go back and start with kindergarten. There are boxes of rocks with more intelligence than you have, DA.

 

[RUFFSTUFF]

What is this? High school? You should go back and start with kindergarten. There are boxes of rocks with more intelligence than you have, DA.

I'll be sure to save you a seat up front next to a window.

 

[SafetyPilotCal]

How do you guys get $7 per fill? Let's say 14 gallons - is 91 octane $0.50 more per gallon where you're at? Around here (CA) we get 87, 89 is usually 87 + $0.10 and 91 is 87 + $0.20. So the extra cost for filling up with 91 vs. 87 is like $3.00 for a full tank.

Here in Texas it's certainly not unusual for 93 octane to be about 50¢ more per gallon than 87. It's about the average here in DFW.

 

[MisterMac]

There is a huge difference between the words recommended and required....

In my Stinger, premium fuel is recommended, while regular fuel is required.

In my Mercedes S550, premium is required.

Consumer Reports and Edmunds, to name a couple sources, have published studies annotating what cars must have premium fuel.

The Stinger does not require premium fuel. Rufus and others can bark at the top of their lungs 24 hours a day, but that will not change the simple facts.

On the Stinger, Top Tier fuel at the regular octane level is required. If you choose, for a plethora of reasons, to run regular fuel, your car will perform just fine and your 10/100,000 power train warranty will remain in effect without question (all else being equal).

Your OM is your Stinger Bible, let it be your solid source of information. Ignore the ill-informed bias on forums like this one.

As your OM states, you MAY lose a little power. Thus, if you are one of the idiots who must race from stop light to stop light, go ahead and put premium in. You still won't win, but you'll believe you have a better chance....

 

[Jklotz]

From the owners manual:

For the optimal engine performance, we recommend you use unleaded gasoline which has an octane rating of RON (Research Octane Number) 95/AKI (Anti Knock Index) 91 or higher. Using Unleaded gasoline with an octane rating lower than RON 95 could result in loss of engine power and increase in fuel consumption. Your new vehicle is designed to obtain maximum performance with UNLEADED FUEL, as well as minimize exhaust emissions and spark plug fouling. Never add any fuel system cleaning agents to the fuel tank other than what has been specified. (Consult an authorized Kia dealer for details.) •

 

[SteveCo]

 

[MisterMac]

Just making glue...

 

[stung cb]

How do you guys get $7 per fill? Let's say 14 gallons - is 91 octane $0.50 more per gallon where you're at? Around here (CA) we get 87, 89 is usually 87 + $0.10 and 91 is 87 + $0.20. So the extra cost for filling up with 91 vs. 87 is like $3.00 for a full tank.

Hello Turbo

How do you guys get $7 per fill? Let's say 14 gallons - is 91 octane $0.50 more per gallon where you're at? Around here (CA) we get 87, 89 is usually 87 + $0.10 and 91 is 87 + $0.20. So the extra cost for filling up with 91 vs. 87 is like $3.00 for a full tank.

Hello turbo AWD. I mentioned the $.50 more per gallon. You live in No. Cal. (the bay area I presume) After checking on Gas Buddy you are correct regarding the smaller difference between gas grades. But...….people in California from the start are being gouged and swindled on their gas prices. Cali gas sellers are just burying the price difference in the grades from the start. I live In Denver.
San Fran reg. grade $3.40
Denver reg. grade 2.35

San Fran. mid grade $3.55
Denver mid grade 2.75

San Fran prem. grade 3.60
Denver prem. grade 3.15

 

[StungBlueGT2]

87 = Performance

91+ = High Performance.

Performance is the action or process of carrying out or accomplishing an action, task, or function.

The Stinger performs as intended on 87.

The Stinger puts out High Performance on 91+.

The lack of high performance is not equal to no performance.

There is your lesson for today.

That’s incorrect and stop making up nonsense to try to justify why you aren’t following manufacturers recommendations.

As the current manual says anything less than premium fuel “could cause a loss of engine power and increased fuel consumption”. That means on premium it will perform as intended, but on 87/89 your causing the engine to protect itself from knock/detonation and it must pull timing to compensate. That in turn makes it less efficient so it loses power and fuel economy. That’s definitely under performing which is not how Kia built and intended the engine to run.

This has been stated and explained dozens of times in different threads.
Gas. 87, 91, 93 Octane?
That one example explains that when AAA thoroughly tested a wide variety of vehicles on required vs recommended fuels it found similar high performance engines gained 8-15% better fuel economy(2-4mpg) and about 10whp more just by using premium. Other car magazines have done similar testing and found some engines gained about 20whp/20wtq on 93.

You and the few people not using the recommended premium fuel crack me up. You chose to spend $5k-10k or $100/m more for the high performance 3.3TT but then use bottom of the barrel gas just to try to save a few bucks. If you were concerned over .30-.50/g difference in fuel prices you should have gotten the less performance oriented 2.0l instead.