Hybrids and 91 Octane Gas?

[AutoMechanic]

Things an auto salesman is good for: 1. Test drive a vehicle. 2. Sell a vehicle to you.
Otherwise, anything you want to know about a vehicle should be researched yourself online or in print. Far too often do salesman give wrong information or answer question incorrectly. You can even see owner's manuals online.

Yeah. I trust one salesman who used to work with me he was a mechanic until an injury ended his career he was very knowledgeable about things. The reason he said to use the higher octane one to keep the knock sensor good and two to prevent gum up of the injectors or fuel tank.

 

[AutoMechanic]

How would it know when to “kick on” if it was turned off? It is after all, the knock sensor. If the knock sensor isn’t sensing, how would it know when it’s knocking?

Well it’s a sensor so it can sense and it’s controlled by the computer so it would make it come on at that point when the engine starts detonating

 

[kschachn]

I am, we always learned it would only kick on if the wrong gas was used to prevent pinging and knocking.

Oh and by the way, it will still affect the timing to prevent pinging even if the “right“ gas is used.

 

[kschachn]

Well it’s a sensor so it can sense and it’s controlled by the computer so it would make it come on at that point when the engine starts detonating

Lol then you’d have to have a knock sensor for the knock sensor to tell it when to turn on. If it’s “sensing” then it’s on.

 

[ctechbob]

Well it’s a sensor so it can sense and it’s controlled by the computer so it would make it come on at that point when the engine starts detonating

Knock sensors are generally something akin to a microphone 'listening' for a very specific frequency and pattern to detect knock. There's no off and on, they are always listening and the computer is always analyzing.

 

[AutoMechanic]

Lol then you’d have to have a knock sensor for the knock sensor to tell it when to turn on. If it’s “sensing” then it’s on.

Interesting I wasn’t aware of that lol I’ve only replaced 2 knock sensors because I mostly work on old stuff so my memory maybe a little rusty on the subject.

 

[AutoMechanic]

Knock sensors are generally something akin to a microphone 'listening' for a very specific frequency and pattern to detect knock. There's no off and on, they are always listening and the computer is always analyzing.

Interesting well glad to know.

 

[Tahoe4Life]

Broward County is running 87 octane in all their V8 Chargers and Tahoe's. They keep their vehicles for over 150K + miles. All are running just fine. I have been running 87 octane [Mobil] for over 95K miles in my 5.3 Tahoe. Used nothing but 87 in my Cadillac and 4.6 Ford Panthers. with close to 300K miles.

For most it is a complete waste of money to burn anything higher then 87. It does not make economic sense for most people. But the oil companies will love you for buying the 89 or 93 octane.

 

[Skippy722]

Broward County is running 87 octane in all their V8 Chargers and Tahoe's. They keep their vehicles for over 150K + miles. All are running just fine. I have been running 87 octane [Mobil] for over 95K miles in my 5.3 Tahoe. Used nothing but 87 in my Cadillac and 4.6 Ford Panthers. with close to 300K miles.

For most it is a complete waste of money to burn anything higher then 87. It does not make economic sense for most people. But the oil companies will love you for buying the 89 or 93 octane.

Recommended and required are 2 very different things.

FCA “recommends” 89 for the 5.7 but states 87 is “acceptable.” The 6.4 and 6.2 HEMI both “require” 91 minimum or expensive things happen. I personally run 89 in my 5.7 hemi because I paid for 395 horsepower and I want all 395 horsepower. The difference is like $6 for half a tank.

GM states “87 or higher” for a Tahoe, while Ford just says use 87 for a Crown Vic. In both of these vehicles you’ll gain nothing running higher octane other than a lighter wallet.

 

[Nick1994]

I didn’t know they still made cars that could run on 87 lol I heard that stopped long ago. I don’t run 87 in any of my vehicles.

I run 87 in my 420hp Genesis

 

[TiGeo]

It's all about timing. Running 87 likely yields *some* minor timing pull/retard/correction under hard loads (WOT for example) based on the knock sensors feedback loop with the ECU. Running 91/93 should prevent some if not all of that allowing you to make *a little* more power. Logging is the only way to see it and folks aren't likely to feel the v slight improvement in top-end power. IF you know how to look at data logs, here are 2 from my VW Atlas with a naturally-aspirated VR6 engine one with 87 and one with 93. Clearly less timing correction with 93. I run 87.

datazap.me | Karstgeo72 | Atlas 93 06-05-2020

datazap.me

datazap.me | Karstgeo72 | Atlas 87 05-08-2020

datazap.me

This is the source of the "*better performance with premium" for many cars in their owner's manuals under the gas or engine specs/performance sections.

 

[Zee09]

My 2016 Cmax hybrid suggests only 87 in the manual
Never a issue. Gets phenomenal mpg

 

[JohnnyG]

As far as the Hybrid goes, it depends on how often the engine runs. When I had my Volt, the engine might run once every 6 months or so, maybe longer. Sometimes it would go so long without running, that it had to enter "fuel maintenance mode", which used up some fuel whether it needed to or not, so that fresh stuff could be put in, and to lubricate various parts of the engine.
The operators manual stated that premium fuel had the benefit from lasting longer in storage (the fuel tank) due to more additives and higher quality overall. It also allowed for better fuel economy for the reasons stated in above posts.

 

[Job]

What is going on is just what it says in the manual. It's your choice of fuels. A lot of cars have and have had such statements for a very long time.

 

[OVERKILL]

I run 87 in my 420hp Genesis

I'm surprised that it permits that! My M5, Charger SRT and all of my SRT Jeeps have called for 91.

 

[Nick1994]

I'm surprised that it permits that! My M5, Charger SRT and all of my SRT Jeeps have called for 91.

Here’s a copy and paste from the owner’s manual. I’ve run 91 in it maybe twice and didn’t notice any difference. I used to run 91 in the Sonata because it would ping otherwise, but no issues with this one.

5.0 engine
Your new vehicle is designed to use only unleaded fuel having an octane number ((R+M)/2) of 87 (Research Octane Number 91) or higher. For improved vehicle performance, premi- um unleaded fuel with an octane number ((R+M)/2) of 91 (Research Octane Number 96) or higher is rec- ommended. (Do not use methanol blended fuels.)

 

[OVERKILL]

Here’s a copy and paste from the owner’s manual. I’ve run 91 in it maybe twice and didn’t notice any difference. I used to run 91 in the Sonata because it would ping otherwise, but no issues with this one.

Ahhhh, so 91 is "recommended" like 89 is "recommended" for my wife's 5.7L. We run 91 in it since Costco only sells 87 and 91.

 

[AutoMechanic]

Surprisingly my 1973 Beetle says use minimum 91 on the gas lid I’m surprised for something that old but I wouldn’t run regular in it anyway

 

[Nick1994]

Surprisingly my 1973 Beetle says use minimum 91 on the gas lid I’m surprised for something that old but I wouldn’t run regular in it anyway

I maintain my aunt's 70' VW Beetle, I'm actually the only one who drives it too. The gas lid says 91 RON, which is 87 octane. Same spec as my Genesis quote above.

 

[4WD]

Raising the compression ratio and utilizing a higher octane gasoline is a legitimate way to improve efficiency. It’s also a lot cheaper and more reliable than the goofy things they’re doing now to try and eek out the last bit of improvement.

I’d love to see one gasoline and one diesel at the pump - would hit a few bumps switching over … but one of the signs of positive change is some discomfort felt along the way …