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2016 CT6 3.0TT Platinum
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117 Posts
Discussion Starter · #1 ·
So the gas station attendant was on autopilot when I specified super and instead chose regular. I normally pay close attention when filling up to verify the correct fuel is selected, but I was conversing with my wife and forgot to watch.

Anyhow, after leaving the station I noticed the car was shaking at stoplights, and the CEL came on after about 20 minutes; that’s when I realized what had happened. I’m not able to hear any knocking or pinging, so the computer must’ve retarded the timing to compensate as best it can for the lower octane. I’ve been taking it easy on the throttle, and filled up with Sunoco 93 after having burned off about 3/8 of a tank on a trip down near Trenton the day after filling up. I also threw in a bottle of Lucas Octane booster (couldn’t find Amsoil Octane booster and I was freaking out a bit). I’m scheduled for a 200 mile round trip up the Catskills and back soon, and should be able to burn off close to the whole tank, at which point I’ll fill with Sunoco 93 again and hope the computer readjusts to the higher octane.

Has anyone else had this happen; if so, how did you make out?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,912 Posts
Don't sweat it. Without running the car hard (beyond normal daily driving in town and on the highway) burn off the perfectly good 87 + whatever mixture you have in there, then refill with your usual fuel.

Good ol' New Jersey knows what's best for you :cool:
 

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2016 CT6 3.0TT Platinum
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117 Posts
Discussion Starter · #4 ·
I’m crossing my fingers that you guys are right and GM had the sense to design the engine to not grenade or require service if run on regular gas once in a while.

The manual states: “If the vehicle has the 3.0L V6 twin turbo engine, use premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. If the octane is less than 91, damage to the engine may occur and may void the vehicle warranty. If heavy knocking is heard when using gasoline rated at 91 octane or higher, the engine needs service.”

I’m hoping to not hearing knocking long enough come back from my trip and fill up with the good stuff again.
 

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2014 SRX4 Prem
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100 Posts
I’m crossing my fingers that you guys are right and GM had the sense to design the engine to not grenade or require service if run on regular gas once in a while.

The manual states: “If the vehicle has the 3.0L V6 twin turbo engine, use premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. If the octane is less than 91, damage to the engine may occur and may void the vehicle warranty. If heavy knocking is heard when using gasoline rated at 91 octane or higher, the engine needs service.”

I’m hoping to not hearing knocking long enough come back from my trip and fill up with the good stuff again.
Yeah, all turbos need premium.
Just lay off it and don't create a lot of boost. She'll be fine!

Plus you already refilled almost half the tank. Drive it a little extra before your trip fill up.
 

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2016 CT6 3.0TT Platinum
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117 Posts
Discussion Starter · #6 ·
This round trip up the Catskills and back will rack up about 200 miles, and I plan on making a little side trip on the way back to Butler to visit High Point Brewery to pick up some Ramstein. I figure that should bring it down to 3/4 of a tank or less being that regular is supposed to afford less mileage than super.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Remember - those turbochargers (or a supercharger) do exactly NOTHING in the way of power increase until you put your foot down. Even small speed increases won't create enough power demand for boost. As long as that throttle butterfly is only partially open and the engine is running in high vacuum you could burn kerosene or panther piss with no side effects.

I doubt seriously that you'll see much, if any, fuel mileage change over the long term.

If you want to feel warm and fuzzy, fill it with a name brand (it makes NO difference which) 91/93 TopTier gasoline at about 1/2 tank. Between that and the previous fill you'll be back in the 91+ range.

 

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2019 CT6-V
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32 Posts
Had a similar experience earlier this year with a supercharged Pontiac Grand Prix GTP I gave my niece after I picked up my CT6-V... I was driving it to Houston and as I climbed the mountains east of Phoenix the car felt like it had no power and the engine was making a lot of noise without a lot of go. I was kind of freaking out that I managed to ruin the engine right when I gave the car away, but then I realized that I had filled up with 87 at my first gas stop. (I always go to Costco for my cars that take premium, and rarely go there for the ones that take regular. I was out of town and didn't stop at Costco, and I simply no-brained it and filled up with 87 like I do any time I'm not at Costco.)

Once I got out of the mountains and onto flat land it seemed to run ok, and when I filled up with 91 in El Paso the check engine light went out and the car was back to normal. First time I'd done that in 10 years of owning it! I was able to warn my niece not to do the same thing. So far the car is still going strong even with a 17-year-old driver, so (at least on that engine) there don't seem to be any lingering effects from my unforced error.
 

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2016 CT6 3.0TT Platinum
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117 Posts
Discussion Starter · #9 ·
Thanks, all; at least now I’m not so worried about destroying the engine.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Sure they do. It's a hot-selling snake oil additive. When I worked part-time at an automobile parts counter I used to sell the stuff (and other snake oils) gladly - Google "spiff". It used to pay my gasoline bill every month.
 
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