Premium Fuel $1.00 (or more) Higher

[SC Maintenance]

I saw 91 for only 20 cents more in TN a couple months ago - so I bought it. It was a Texaco station I think?

I never paid any attention until I started reading this board. You all made my OCD worse if thats possible. I even took this pic not long ago. This is a pretty typical spread around here.

 

[SevenBizzos]

I use Premium in all my cars now (by perceived performance [not claiming HP gain] and by tuning). It's been $1.00 to $1.10 more a gallon over 87 for many years. Basically it's running $4.69 - $4.99 a gallon ATM.

 

[alarmguy]

I use Premium in all my cars now (by perceived performance [not claiming HP gain] and by tuning). It's been $1.00 to $1.10 more a gallon over 87 for many years. Basically it's running $4.69 - $4.99 a gallon ATM.

Using premium in a regular octane vehicle does it no good, possibly even lead to piston deposits though I would assume the vehicle system might be able to adjust. Im just saying I would look into the subject.

The slower burn of premium might leave behind deposits in lower compression engines that do not need premium. Do to a slower burn of high octane fuel it could leave unburnt fuel in the chambers. I do know in motorcycles this was an issue at one time and still might be, been a number of years now that I looked into it.

 

[MNgopher]

Usual spread here is around 60 cents to a dollar. Many of the dollar spread stations are E0 91 octane. Don't want ethanol, pay to play...

The station i fill at for canadian trips i do premium E10 in the truck (ecoboost towing) and E0 premium in the boat... usually 30 cents more a gallon the the E0 premium than E10 premium.

 

[SevenBizzos]

Using premium in a regular octane vehicle does it no good, possibly even lead to piston deposits though I would assume the vehicle system might be able to adjust. Im just saying I would look into the subject.

The slower burn of premium might leave behind deposits in lower compression engines that do not need premium. Do to a slower burn of high octane fuel it could leave unburnt fuel in the chambers. I do know in motorcycles this was an issue at one time and still might be, been a number of years now that I looked into it.

I don't own any "regular octane" vehicles.

 

[The Critic]

This must be a non-CA issue? I have always seen a 40-75 cents delta between regular and premium. It's often around 60 cents, even less if you use Costco.

To me it's an engine longevity issue. If you're planning to keep a vehicle longer than the intended 150K, I simply do not trust the efficacy of knock detection to dial back timing under all conditions. If you buy a car that needs 91, just plan on putting 91 in it.

 

[Jetronic]

An old geezer, speaking generally, told me engines benefit from premium fuel (a cooler burn).

Engines today push the envelope and have knock sensors (and other programming?) to save us.
I feel a little zipedee doo da in the tank can help a regular drinker run brighter.
A guru on the Ranger forum approved my idea to add a little high test before some Summer driving.
It's likely engine dependent.

My 1.5T can knock sometimes when it's hot while using 95 RON. it only lasts a second or so, so the knock sensors catch it and the ecu reacts. But I don't get it with 98 RON, which costs about 15% more. So when it's hot I run 98.

 

[repairman54]

To me it's an engine longevity issue. If you're planning to keep a vehicle longer than the intended 150K, I simply do not trust the efficacy of knock detection to dial back timing under all conditions. If you buy a car that needs 91, just plan on putting 91 in it.

2X, its already been knocking by the time the system detects it and reacts. Multiply that over the miles adding up.

 

[MNgopher]

2X, its already been knocking by the time the system detects it and reacts. Multiply that over the miles adding up.

And I assume then the thought is you believe it isn't doing this on higher octane fuel?

On a Ford Ecoboost, it is always looking at this - even on premium - to extract the most potential from the present fuel. 138,000 miles of monitoring, and I've only ever had one tank of gas that nearly maxxed out the Octane Adjustment Ratio - where this wouldn't happen...

 

[PandaBear]

I don't expect it to stay 20c extra forever. Gas was $2 / gal back then when it was 20c extra so that's 10%. Today here gas is $4 / gal typically if not $4.50 so it make sense they are also around 10% more.

I'm sure costco charge about what cost them, but a lot of the cost a station have is not just the gas but how they run the station like labor. If everyone in my area charge that amount it is likely the competitive market cost, I'm not going to complain. I still use it in one car that requires it but I wouldn't just to sleep better at night.

 

[The Critic]

And I assume then the thought is you believe it isn't doing this on higher octane fuel?

There is always some quantity of knock events. It is generally minimal on the preferred grade of fuel.

 

[HighHy21]

That's why I'm back to a car that requires regular 87 AKI, and use Top Tier 99% of the time

 

[The Critic]

At the end of the day, it's an extra expense to drive a car that you presumably like. It is no different than spending an extra $50/mo to buy the brands of groceries you prefer.

 

[Chris142]

Thats 91, right? Here, our local 4 competing stations, including the QT, all have a .50$ spread between regular 87 and premium 93.

Ya 91 is the highest we get. All our fuel is E10 regardless of octane

 

[ATex7239]

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.

 

[tbm5690]

No mid grade here, just 87 E0, 87 E10 and 91 E0. 60¢ spread between 87 and 91 E0.

 

[Rmay635703]

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?

Mid grade is considered the same octane as antique “leaded”
Mid grade is spec’d in my old NA Dodges manual for some reason though it’s very rare I ever ran it.

My experience at 1200-1500ft elevation is that my one car that supposedly “requires “ premium runs with similar knock counts on 88e15, especially in the winter.

Premium is extraordinarily expensive in this area so I don’t touch it, 93 is very rare regionally. So 88e15 mid grade is what I use.

My local fuel tanker depot claims that the necessary materials to even make 87e10 are rare and short in supply which is why ethanol is being pushed, farm folk may figure it’s for them but it’s actually because we have shortages of acceptable fuel feed stocks, especially impacting the Midwest. Meaning it’s a pure business decision. This year our ethanol content in fuel has been running near the legal limit since February. Per ethanol test kits e10 almost always had 3% this time of year, no more.

 

[ProbeGT]

$2.58 regular (87), $3.18 premium (93) at my local Sam's Club. I mix it at 40/60 ratio to achieve 91 octane. All my cars require premium and run like crap on regular (low power, valve chatter). They run perfect on 91 or 93. So I make my own 91 and save a few bucks.

I thought about mixing regular with E85 until I watched the Oil Geek's video, warning about ethanol's metal-attacking properties and engine oil degrading properties.

 

[Dave Hess]

I don’t mind spending extra for 93 octane if my engine needs it.

If not 87 octane is good for my daily beater.

 

[MNgopher]

There is always some quantity of knock events. It is generally minimal on the preferred grade of fuel.

Lets probe that for a minute.

Ford Ecoboosts use a parameter called the Octane Adjust Ratio (OAR). The parameter varies between 1 (awful low quality / low octane) to -1 (High Octane). Through this parameter, the engine adjusts timing to take advantage of the fuel the computer is perceiving its being fed to the engine. This is how / why the ecoboost lineup of engines develops more hp on higher octane fuels - and has been demonstrated in multiple studies and tests all while preserving themselves while running non-premium gasoline.

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...

So again, in a system where the engine can adjust based on fuel octane, unless you always have the OAR pegged at -1.0, its going to find that knock threshold and adjust the ratio up and down on it.. And in 9+ years and 139,000 miles on my F150, the highest I:ve ever gottent the OAR was -.97 - meaning there was still room for it to adjust timing and find knock events on the fuel it had... (FWIW, the -.97 was on some BP 93 octane. 93 octane is not easy to find around here - most premium is 91 octane).

Perhaps in vehicles that cannot take advantage when they get higher octane and only self preserve when the knock sensor detects this isn't true - but there are a ton of vehicles on the road that their preservation strategies depend on finding this tipping point meaning its always happening...