Fuel Type

[Garylh1018]

The manual for mine states that a minimum of 91 octane is recommended for optimal engine performance. It also states that using fuel with less than 91 octane could result in less performance and decreased fuel economy.

I would do whatever you think is acceptable, but I'm running nothing but premium in mine.

I was going to run mid - grade and then premium every 4th tank fill to see how that works, and if it doesn't work well and there is a noticeable change, then I will go to running all premium.

 

[Garylh1018]

There is a big difference between recommended and required. We run 89 with no problem, my wife's Stinger GT1 is a daily driver, extra performance from 93 octane not needed.

Thank you!

 

[ChaneRZ]

Wide Open Throttle

 

[robh693]

I commented on this thread earlier since my wife uses 87 in her GT with no issues but what I found surprising was the fuel economy loss when dropping from 91 octane to even just 89. I just completed a 3000 mile trip and and used 91 going there averaging 31 mpg at 80 mph (drive mode made no difference at that speed). On the return trip I used 89 exclusively and couldn't break the 28 mpg average. I would never have guessed the octane made that big a difference.

 

[stoopid]

I commented on this thread earlier since my wife uses 87 in her GT with no issues but what I found surprising was the fuel economy loss when dropping from 91 octane to even just 89. I just completed a 3000 mile trip and and used 91 going there averaging 31 mpg at 80 mph (drive mode made no difference at that speed). On the return trip I used 89 exclusively and couldn't break the 28 mpg average. I would never have guessed the octane made that big a difference.

Did you lose elevation in one direction? Gain elevation or have headwinds in the opposite? There could be an explanation other than the fuel octane change.

Running the engine at low and constant RPMs at 80MPH shouldn't yield much of a difference.

 

[robh693]

Nope. Weather conditions were similar and roads traveled were equal level in both directions.

 

[stoopid]

Nope. Weather conditions were similar and roads traveled were equal level in both directions.

Can I ask what the itinerary was? North Dakota to Texas and back? I'm not aware of many roads in the US (or Canada) where 3,000 miles doesn't have mountains somewhere on the route. Temps identical for all of a 3,000 mile multiday trip? Air conditioning certainly drags on the engine.

 

[Travis Wills]

I don't know if anything will maximize the mileage on that gas guzzler. I was just curious if anyone has ran mid-grade in their GT1 or GT2 for any length of time and noticed any real difference. As far as engine damage, what I meant was if it left any type of engine build up. If it doesn't, then I will start using mid-grade, but nothing less. Thank you for your response!

I did 0-60 mph and 1/4 mile pulls with 87 Octane before. It wasn’t any slower when the car was completely stock. However, once I added aftermarket snorkels I couldn’t match my 93 Octane times with 87 Octane in the tank.

Without mods and with low IATs 87 performs the same. Once you mod anything performance wise or if IATs start to climb then higher Octane will be required.

 

[RM7]

The more high strung the engine, the more it needs higher octane. These cars crave high octane fuel, but they will run "just fine" on lower octane, the computer adjusts for it, it's not a big deal. You lose efficiency and power. Just basic stuff.

My Elantra GT N-line 1.6T was a different animal, that engine was tuned to give full HP and performance on regular fuel. It had a weak boost control solenoid though, so it wasn't smooth accelerating and I upgraded that and did a blue-spark piggyback, that worked well, but in that configuration I only used high grade, since it was putting out a little more.

 

[rpoffen]

I used to have a 1998 Mustang Cobra with the 4.6l DOHC V8 engine. I always used the recommended premium (93, then 91 when CA phased out 93) fuel, but I could always tell the difference between bargain gas stations and top tier, particularly Union 76. I got better mileage with the Union 76 (22.5 vs 21.5) than bargain gas stations. One possibility was that at the time, most gas in CA had MTBE added as an oxygenate, Union 76 was the first to phase it out when the government in all their wisdom realized MTBE was a carcinogen and was contaminating the groundwater. Among the other bad things about MTBE was its affinity for eating through fuel lines and reducing mileage.
This was noticed consistently many times over the 160K miles I owned the car.

 

[Stephen Brubaker]

I run only 91. Would like to try some 93 but the only 93 here in town is sold at the shell station and they want an arm and a leg for it. Also it is a 10% ethanol blend and I don't use ethanol in any of my cars.

 

[Travis Wills]

I run only 91. Would like to try some 93 but the only 93 here in town is sold at the shell station and they want an arm and a leg for it. Also it is a 10% ethanol blend and I don't use ethanol in any of my cars.

Just curious why you wouldn’t use Ethanol in any of your cars?

 

[stoopid]

... Union 76 was the first to phase it out when the government in all their wisdom realized MTBE was a carcinogen and was contaminating the groundwater. Among the other bad things about MTBE was its affinity for eating through fuel lines and reducing mileage...

So the government made a bad decision when they phased this out?

 

[rpoffen]

No, they made a bad decision to require an oxygenate and approved MTBE in the first place.

 

[stoopid]

No, they made a bad decision to require an oxygenate and approved MTBE in the first place.

It appears that the health effects still aren't fully understood, the decision to stop using it also varies from state to state. They can't block something from being used in its intended manner until they know it's harmful when used in that manner. If they banned it without evidence of harmful effects they'd get shit for that, too.

Methyl tert-Butyl Ether (MTBE) Factsheet | National Biomonitoring Program | CDC

The federal requirements do not specify any particular oxygenate, but because MTBE was a relatively inexpensive means of adding oxygen to gasoline, and because it had other favorable properties as a fuel additive, MTBE became the dominant oxygenate in the U.S. fuel market, with ethanol in distant second place.

The Paradoxes of MTBE

Abstract. A widely used gasoline additive, methyl tertiary butyl ether (MTBE), has been controversial, in part because of concerns about potential inhalati

academic.oup.com

So of course the oil companies went with the cheaper option.

 

[G-777924]

I personally put Hawaii's 91 octane limit from Shell, along with some Boostane to bring it up to 114-116 octane, been getting 550+ on my range now(91's + Boostanes) for the past several weeks compared to the normal 350-370 range I usually get from just 91's on my stock 2020 gt1 rwd, down side is the boostanes cost $30+/fuel up so you can do the math but higher octanes means happier engine, although too much octane is also bad, your car just wouldn't want to f*cking run

 

[RM7]

You are not getting 114 octane out of a can of boostane. That's not how it works. You also need to be sure you are not using leaded boosters or boosters with methylcyclopentadienyl manganese tricarbonyl. The "not for street use" or "racing use only" boosters tend to have these compounds that will foul your engine, plugs, emissions, valves, etc.

 

[DonD]

I just don't understand why people buy performance cars and then try to go cheap on fuel.

Ok, so you may get by with it but say you're driving on a hot day and you decide to pass another car and midway through it, you realize you screwed up.

So you floor it. Are you going to get detonation/pinging or will the engine yank off a lot of timing. In the former, bad for the engine, in the latter, your pass may be a real white knuckle affair.

I'll stick with the recommended octane and I choose Shell whenever I can get it, otherwise Exxon or Chevron. Why, I've been feeding our other car, a Pontiac G8GT with a slightly detuned Corvette engine, Shell for several years and it has smoothed the idle out noticeably. Don

 

[rpoffen]

Unfortunately, some states (like California) are not blessed with being able to get anything over 91, except at maybe a handful of stations in the state that carry 100 racing fuel (at $10/gal).
So, I keep it on map 1 for around town driving on 91, and on the days I go to the track, I get a few gallons of the race fuel (still about 30 minutes out of the way), and use a higher map while at the track.

 

[G-452316]

I don't know if anything will maximize the mileage on that gas guzzler. I was just curious if anyone has ran mid-grade in their GT1 or GT2 for any length of time and noticed any real difference. As far as engine damage, what I meant was if it left any type of engine build up. If it doesn't, then I will start using mid-grade, but nothing less. Thank you for your response!

Honestly, running my GT2 in “Smart Mode” gets me the best gas mileage due to the “coasting” feature. I can get 21-29 hwy and 20-24 city in that mode. Traffic is congested in Vegas so driving fast isn’t the best idea commuting to work. I use 91 gas. Of course, Sport Mode is the most fun though.