Premium Fuel $1.00 (or more) Higher

[The Critic]

The OAR adjusts based on feedback from the knock sensor. The engine is constantly monitoring for knock type events and when it sees them, adjusts the OAR for lower Octane. When it doesn't, it adjusts the OAR up until eventually it finds them again...

But is it? That's the crux of the issue. It is my understanding that knock detection is not always active; it is only active under conditions where the detonation is most likely to cause damage and have a negative impact towards the intended service life.

 

[MNgopher]

But is it? That's the crux of the issue. It is my understanding that knock detection is not always active; it is only active under conditions where the detonation is most likely to cause damage and have a negative impact towards the intended service life.

If it isn't active, how or why would the OAR adjust up or down? (again, speaking for Ford ecoboosts which is the environment I live in...)

Some reading if you are interested...

https://stratifiedauto.com/blog/und...ons-in-your-high-performance-ecoboost-engine/

 

[14Accent]

But is it? That's the crux of the issue. It is my understanding that knock detection is not always active; it is only active under conditions where the detonation is most likely to cause damage and have a negative impact towards the intended service life.

I got curious about this, so I peeked in the service manual for my '95 Cadillac Seville and the way the system is described it sure seems like knock detection is a full-time monitored input. The service manual even explains how it tests the knock sensor continuously during operation to verify it's functional: under low load conditions, the PCM will add timing in .3 degree increments (up to a max of 21 degrees) and looks for a response from the knock sensor. If no response is received, it sets a code and forces base timing.

Unfortunately, only the VIN 9 engines have a data PID for "Detected Fuel Octane". My VIN Y doesn't support that display, but it will show degrees of timing being pulled and knock counts detected. I'll have to make a pull with the data parameters pulled up on the dash and see how well the 91 octane is holding up.

 

[maduroman]

It's only $.30 a gallon more here

Yeah , but you're already getting screwed lol

 

[walterjay]

At BJ's today

 

[Skippy722]

I don't understand who actually needs to use mid-grade gas (ie 89 octane) AND why anyone would be willing to pay say 50 cents more per gallon?

5.7 HEMI’s recommend it…. Unless it’s a challenger with a manual, those REQUIRE 91.

That being said, I never noticed a difference in any of the cars or SUV’s with a 5.7 between 87 and 89… my truck however I notice so it lives on 89 or 93 if 89 ain’t available. At absolute worst, it’ll cost be an extra $13-$26 to fill my tank from E vs 87. There’s easier ways to save money.

 

[Blagoje]

At absolute worst, it’ll cost be an extra $13-$26 to fill my tank from E vs 87. There’s easier ways to save money.

Fair warning, making statements like this might get you tarred and feathered 'round these parts friend

 

[Skippy722]

Fair warning, making statements like this might get you tarred and feathered 'round these parts friend

I paid for 395hp, I want all of it!

 

[The_Jeff]

There was a Honda Accord probably 20 years ago now that made more hp and fuel economy in a new calibration thanks to new knock sensors, per a Honda press release. Same basic engine, just better tech.

My 95 Saturn, crude even in it's day, would get dead spots in acceleration I could feel. Those were historical knock events caused by swallowing a glug of (low octane) motor oil and burning it. A ring job cured the issue. I could also seafoam it and disconnect the battery, but the first knock would be remembered for hundreds of miles.

GM had knock sensors in the 1978 Turbo Regal, and the 1981 1/2 ton truck with the 305. These vehicles didn't even have feedback carburetors! The tech has been out there for a while and getting better.

 

[14Accent]

I pulled up the knock retard data display on my way home today and did a couple 2nd and 3rd gear 60-80ish pulls. The most I saw was 1 degree, mostly hovering around a third to a half a degree. That's with a fully warm engine and 60 degree ambient temp.

If the PCM is pulling timing (however slight it may be), even while using premium, I figure I better keep using it.

 

[Carmudgeon]

5.7 HEMI’s recommend it…. Unless it’s a challenger with a manual, those REQUIRE 91.

That being said, I never noticed a difference in any of the cars or SUV’s with a 5.7 between 87 and 89… my truck however I notice so it lives on 89 or 93 if 89 ain’t available. At absolute worst, it’ll cost be an extra $13-$26 to fill my tank from E vs 87. There’s easier ways to save money.

Who doesn't like to save money?

But, if that's what the vehicle requires, that's what it gets, and that's about as much thought as I devote to it.

The same could be said for every other facet of owning, registering, insuring, and feeding a vehicle. The time to consider these things is before you make your purchase decision.

 

[Skippy722]

Who doesn't like to save money?

But, if that's what the vehicle requires, that's what it gets, and that's about as much thought as I devote to it.

The same could be said for every other facet of owning, registering, insuring, and feeding a vehicle. The time to consider these things is before you make your purchase decision.

I don’t eat out, drink, or smoke… turning gasoline into noise is my vice!

But yes, absolutely agreed. My aunt bought an Audi that requires 91, she was floored when I confirmed that with her.

 

[wemay]

Same here. Now, over $1.10 higher in same areas. So is ethanol free gas.

Premium being 93 octane.

 

[javacontour]

I was passing through Litchfield, IL on 29 August and ran across this gem:

 

[Patman]

^^^ That’s because it’s on Corvette Drive

 

[javacontour]

^^^ That’s because it’s on Corvette Drive

The Mr Fuel across the street doesn't seem to have the same view on their fuel.

 

[97prizm]

In the 80s and 90s, maybe even into the 2000s, premium fuel was 20 cents more than regular in my area, and mid-grade was 10 cents more.

Now, in my area (TN), it’s at least a full dollar more. Sometimes even $1.10.

I can’t remember exactly when this became a thing. Seems like it wasn’t that much 5 years ago when I had my WRX (always used premium) and my wife had her Civic turbo (she always used premium).

My cars can all use 87, but the Elantra N makes 20-25 more horsepower on premium. But it’s not worth it while using it to commute 92 miles per day. I could stomach $5-6 per tank. But an extra dollar per gallon seems nuts.

If I know I’m going out for a fun drive, I’ll spend the extra $12-13 per tank.

Seriously though, I know there are some oil industry folks here.

Is there any justifiable reason for this?

Is $1.00 equivalent to $.20 (what it was around 1995 when I got my first car), in 2025 money?

From my reading fracking, at least in Colorado is part of it. Second didn't a lot of states (Or maybe just California) got rid of toluene as a cheap octane booster.

 

[john_pifer]

It’s been a while since I’ve needed an 89 or 93 but I recall QT always being a little cheaper than everywhere else. I checked gas buddy and seems to still be holding true. QT 93 is 40 cents cheaper than XOM 93 and Shell 93 in my town and it’s TT rated. The 87 is the same for all three locations at $2.99.

QT also reliably has 90 octane E0 in my area. I use it in my mower.

 

[SwampSurvivor]

Right around home it's like $1.20 more per gallon, but it's also ethanol free. So I end up using it in everything that has a carburetor or isn't frequently used.
I have seen it elsewhere for a bit less than $1 a gallon more but never buy it. The only reason I buy it near home is so I can avoid ethanol.

 

[zzyzzx]

Already on my list of reasons not to own a vehicle that requires premium gasoline.