Regular unleaded vs Premium gas

[BleedNBlue]

93 Octane. At the lake (LOTO) 91 Octane with no corn (pure gas).

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[Linkster1666]

Every time you run 87 Octane in a Gen III Coyote, that detonation is beating the crap out of your engine, PERIOD.

So when you come in here asking "Why does my engine have a loud thud?" in 18 months, imma chuckle just a bit.

 

[tokuzumi]

Unless you have a boosted vehicle, or you have an aftermarket tune that requires a certain grade of fuel, driving with a lower octane fuel is not going to shorten the duration of the engine. Maybe if these cars came with a carb from the factory, sure. Thinking the engine is going to have problems after 18 months of using 87 octane makes me .

 

[The_Phantom]

Every time you run 87 Octane in a Gen III Coyote, that detonation is beating the crap out of your engine, PERIOD.

So when you come in here asking "Why does my engine have a loud thud?" in 18 months, imma chuckle just a bit.

False.

Stop debating this issue and read the only information that matters: The owner's manual provided with your car.

It clearly states it was designed to run on 87 octane. This from the engineers who have all the insider knowledge on the engine and know EXACTLY what tolerances it was built to handle. Do you honestly think that a company as cheap as FoMoCo is would make a statement like that knowing they will be required to stand behind it legally? No.

It goes on to say that "for best performance, 91 octane is recommended."

It's very, very simple. If you want to use 87, it's not going to hurt anything at all. If you hear any pinging, they recommend filling with mid-grade for a tank and then switching back to 87. For those of us running Tier 1 fuel, pinging on 87 would be a VERY rare thing. If you're running "Gary's Gas Hut" or something, then yeah...it's probably going to ping on the cheap stuff.

if you want every horsepower, then buy 91. Higher than 91 is a waste. However, as I stated, where I live it's 87, 89, 93 so 93 becomes the choice for best performance. Absolutely no one here is pushing their car to the limit on their daily commute. But some people like the placebo effect of running higher octane so they know they have the capability of using 100% of the power if they want to. Others don't feel the expense is worth it for the minimal horsepower gain that they will never use while crawling down the freeway at 10mph in rush hour traffic, so they go 87.

Neither person is wrong for doing what they want. But when you throw out a statement that basically says, "I know more about this motor than the guys who designed and built it, and.....", well.....that's just BS.

 

[ctandc72]

Every time you run 87 Octane in a Gen III Coyote, that detonation is beating the crap out of your engine, PERIOD.

So when you come in here asking "Why does my engine have a loud thud?" in 18 months, imma chuckle just a bit.

hmm.... NO.

Do you understand how modern knock sensors and ECU's work? This isn't the 70's and 80's. The engine will run just fine. Do you really think for one minute that Ford would release an engine in the Mustang GT (it's not exactly hard to buy one) that wouldn't run on 87 Octane? I'm not debating what each person does with their own car / money. But your statement is seriously ridiculous.

 

[ctandc72]

False.

Stop debating this issue and read the only information that matters: The owner's manual provided with your car.

It clearly states it was designed to run on 87 octane. This from the engineers who have all the insider knowledge on the engine and know EXACTLY what tolerances it was built to handle. Do you honestly think that a company as cheap as FoMoCo is would make a statement like that knowing they will be required to stand behind it legally? No.

It goes on to say that "for best performance, 91 octane is recommended."

It's very, very simple. If you want to use 87, it's not going to hurt anything at all. If you hear any pinging, they recommend filling with mid-grade for a tank and then switching back to 87. For those of us running Tier 1 fuel, pinging on 87 would be a VERY rare thing. If you're running "Gary's Gas Hut" or something, then yeah...it's probably going to ping on the cheap stuff.

if you want every horsepower, then buy 91. Higher than 91 is a waste. However, as I stated, where I live it's 87, 89, 93 so 93 becomes the choice for best performance. Absolutely no one here is pushing their car to the limit on their daily commute. But some people like the placebo effect of running higher octane so they know they have the capability of using 100% of the power if they want to. Others don't feel the expense is worth it for the minimal horsepower gain that they will never use while crawling down the freeway at 10mph in rush hour traffic, so they go 87.

Neither person is wrong for doing what they want. But when you throw out a statement that basically says, "I know more about this motor than the guys who designed and built it, and.....", well.....that's just BS.

I agree except for this part:

"Higher than 91 is a waste."

Check out dyno numbers - not just on the Mustang. On modern performance engines, the ECU will KEEP feeding the engine timing (more power) as long as knock isn't detected. It's not hard. Same quality 93 Octane vs 91 Octane will take more timing, which = more power.

Now if you were computing some power vs money spent diametric - maybe it's "not worth it" to certain people.

Hell, if memory serves, Ford and a few other manufacturers actually use different grades of gas for MPG and HP ratings. If I remember non-ethanol 87 octane was used for MPG Rating and 93 Octane for HP rating. And that's the factory numbers.

 

[Bikeman315]

So what we need is what the old Jaguar XJ had, two gas tanks. One for 87 (mileage) and one for 91/93 (performance) Of course when you hit the switch and forget to fill-up tank 1 you are in deep shit.

 

[tokuzumi]

I can imagine that switched only worked intermittently...because Jaguar.

 

[ctandc72]

I can imagine that switched only worked intermittently...because Jaguar.

Lucas - the Lord Of Darkness.

 

[Linkster1666]

Opinions vary.

 

[The_Phantom]

Opinions vary.

Facts don't.

 

[ctandc72]

Totally forgot what my buddy used to say about British "electronics" (he had a thing for old Triumphs and the like) ...lucas switches have three positions. On, off and maybe.

 

[Linkster1666]

Just because you can, doesn't mean you should.

 

[The_Phantom]

Just because you can, doesn't mean you should.

 

[ctandc72]

Opinions vary.

They do. But trying to argue that Ford would produce a mass production car (Mustang GT) with an engine (5.0 Coyote) that would possibly be damaged running 87 Octane (the most widely available gas in the country) which could potentially cost them hundreds of thousands of dollars in warranty repair is beyond a stretch. In fact - odds are - Ford tested the MPG rating for the Mustang GT 5.0 using ethanol free 87 Octane.

https://www.fordnxt.com/news/ford-uses-different-octane-gas-to-test-for-horsepower-mpg/

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