2018 GT MPG 87 vs. 93 octane

[bootlegger]

I may have not have explained it like this, but this is the reason why I do 91-93 octane, Not because it’s “premium”. I hate it that it is expensive, partly due to the fact that people use it even if they really don’t need it.

Most fuel suppliers actually add more detergents and other additives in premium fuel. So, it's not always just an octane thing. I do agree that the label premium can be a bit misleading. My guess is that it was used to help market more expensive fuel.

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[jpogi]

Most fuel suppliers actually add more detergents and other additives in premium fuel. So, it's not always just an octane thing. I do agree that the label premium can be a bit misleading. My guess is that it was used to help market more expensive fuel.

I can't think if any supplier that actually do this nowadays without advertising it. Even the Shell with their Nitro+, states "all grades of fuels have equal amount of detergents greater than Tier One."

 

[bootlegger]

I can't think if any supplier that actually do this nowadays without advertising it. Even the Shell with their Nitro+, states "all grades of fuels have equal amount of detergents greater than Tier One."

I haven't seen that claim from Shell. Actually, they differentiate between a 10k mile cleanup with regular "Nitrogen Enhanced" fuel from them and the V-Power. They are at a very high dose, so it wouldn't shock me to see similar detergent levels. They add other additives at a higher level in the 93. V-Power has a friction modifier, while the regular 87 doesn't. It has been 7 years since I have seen their additive formulation.
It is true that many advertise it. Not all make that advertising well known. Spinx tends to have a little label on the pump.

 

[GregP27]

The owner's manual for my 2019 says run 91 octane minimum.
We also have a new Acura MDX six-cylinder that ALSO says run 91 octane. It is some 290 HP.

Any engine running 12.0 : 1 should NOT be run on 87 octane gas unless maybe it is someone else's car!

 

[jpogi]

I haven't seen that claim from Shell.

It is on a 1X1" small sticker with very small letterings placed around the 87 regular button.

 

[accel]

If it's anything like the 2015-2017....not much.

https://newsroom.aaa.com/wp-content...ium-Fuel-Phase-II-Research-Report-FINAL-2.pdf

nice research.

one thing I could not find in the printing was: how long did they drive the car on premium before running tests?

I think Mustang will not advance ignition right away. There's some learning involved.

Some who installed power packs and had detonation issues reported, that timing adjusted to the point of not detonating anymore several tanks of fuel and several hundred miles later.

Similarly, it might need more time to advance than just next tank of fuel.

 

[Flyhalf]

who ever is running less than 91oct in a 12:1 compression ratio engine that rev up to 7500 should buy a Tesla.

 

[thunderstrike]

First few hundred miles I put 87 octane gas, but engine kept knocking, especially starting out in first gear. I run 93 now.

The Ecoboost ran fine on 87, but I don't understand how other GTs are running okay with it.

 

[millhouse]

First few hundred miles I put 87 octane gas, but engine kept knocking, especially starting out in first gear. I run 93 now.

The Ecoboost ran fine on 87, but I don't understand how other GTs are running okay with it.

I'd change to a different gas station or take your car in for service. Your car should not be knocking on 87 octane.

 

[Ebm]

The owner's manual for my 2019 says run 91 octane minimum.
We also have a new Acura MDX six-cylinder that ALSO says run 91 octane. It is some 290 HP.

Any engine running 12.0 : 1 should NOT be run on 87 octane gas unless maybe it is someone else's car!

That's simply not true. Please don't spread bullshit on this forum.

 

[Sigma6]

I try to run 91 premium non ethanol gas whenever I can.

 

[thunderstrike]

I'd change to a different gas station or take your car in for service. Your car should not be knocking on 87 octane.

I drove from Virginia to Alabama on 87 using different brand gases. 87-belivers, go ahead use it.

 

[Scott.lester1]

Most people can absorb $270/year, but the question for most is...is it worth it? I can't fault anyone that says yes...but most people would flip their shit if their insurance went up $270/year...or if their phone bill went up $270/year.

It's all in the value of what the $270 gives you. For me, it's closer to $500. ;)...and it's a no-brainier.

Again, I don't have any data for the MY18....but the link I posted shows the dyno for the MY17, and the difference is so insignificant that it can't be felt but only measured.

I've said it before...using Top Tier fuel is far more important for these cars than running premium.

well you do get performance out of 93 so if you take the mindset that pretty much anyone would pay that for a modification to get that horsepower

 

[JCFoster]

I drove from Virginia to Alabama on 87 using different brand gases. 87-belivers, go ahead use it.

We will, thks

 

[Gregs24]

No, no, no, no, and NO

This is wrong. Higher octane fuels do NOT take longer to burn. This is NOT why timing needs to be advanced for higher octane fuels. It's completely backward. Timing can be increased BECAUSE of higher octane fuel.

Why??

It's called mean piston speed. A gasoline/air fuel mixture can only burn so fast. Increasing gasoline's octane rating does not affect the burn rate one little bit. Higher octane fuels (as already discussed) resists pre-ignition/detonation, period. Here's the deal: As an engine is revved higher and higher in order to make more horsepower, piston speed increases. It increases on the up-stroke and the down-stroke. As piston speed increases, the initiation of spark in the combustion chamber needs to happen sooner so that the piston on its down-stroke does not outrun the flame front of the fuel/air mixture that has been ignited.

A higher octane fuel, especially in a high-compression engine, simply helps to prevent the fuel/air mixture from self-igniting prior to the optimum moment of spark that would otherwise be initiated by the ignition system as designated within the programming of the car's ECU.

This is probably the only post in the thread worth reading !

The Octane rating does NOT have any connection with calorific value (energy content) and so premium fuels do not directly produce more power. What the octane rating does relate to, as mentioned above, is the fuel burn. It may seem hard to believe considering the time available but petrol needs to burn and NOT explode. Higher octane fuels have more controlled burn characteristics which mean they enable more extreme compression ratios that would otherwise encourage explosions rather than burning. The main impact is actually improved engine torque and driving characteristics which can have a knock on effect on fuel consumption.

The additional additives in premium fuels do contribute to better long term engine durability, both in the engine itself and in the fuel systems. Certainly in Europe they do contain more cleaning products.

In the real world you will not notice a huge difference from one fill to the next but for long term use it simply comes down to cost benefit on engine and fuel system durability together with incremental gains on driveability and fuel consumption. Some will choose to use premium fuels, some not and there are pros and cons to both options

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