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Just got my XT5 with the 3.6 on Saturday. The manual says gas with an octane rating of 87 (regular) is acceptable. The Cadillac salesmen said, "Yes, but..." Their explanation was that 87 is like Coke and 93 is like water. Your body will run on either one, but it will run better on water. Cadillac are like that in they will run on either but will run better on 93.

My wife's Escalade with the 6.2 says 93 is recommended but not required. However, it's a much larger engine. My intuition says GM probably uses the 3.6 in a lot of other applications all the way down to Chevys, so 87 is likely fine.

What's the general consensus on this?
 

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I have been using 87 without any problems. Once in a while throw in 89 or 91.

As the manual says 87. And as Excalibur said you will save on your wallet. :)
 

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2020 XT5 Platinum in Red Horizon Tintcoat and Maple Sugar interior
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87 octane is all you need to use. Anything more than that is wasting money and will serve no benefit. 93 octane fuel does not "clean your engine" any better than 87 octane. If your engine is not knocking or pinging on 87 octane, and it shouldn't with the 3.6 engine, then 87 octane is what you should use.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Use the fuel recommended in the owner's manual and run a TopTier type -

TOP TIER™ Gasoline Brands

- read the intro and fine print - dispels many myths about gasoline. 87, 89, and 91/93 are all "good" for the engine recommendation. One is not "better" than the other.
 

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Just got my XT5 with the 3.6 on Saturday. The manual says gas with an octane rating of 87 (regular) is acceptable. The Cadillac salesmen said, "Yes, but..." Their explanation was that 87 is like Coke and 93 is like water. Your body will run on either one, but it will run better on water. Cadillac are like that in they will run on either but will run better on 93.
Salesmen are just that - sales people. The engineers who spent thousands of man-hours and millions of dollars designing the engine know what octane it needs. If the Owner's Manual says 87, then 87 is all it needs, and by saying otherwise the salesmen are simply displaying that they should stick to talking about things they understand.

So, as others have already replied, run 87.

My wife's Escalade with the 6.2 says 93 is recommended but not required. However, it's a much larger engine. My intuition says GM probably uses the 3.6 in a lot of other applications all the way down to Chevys, so 87 is likely fine.
The octane requirement has absolutely nothing to do with the engine displacement. It's all a matter of how the engine is designed and tuned - cam timing, spark timing, dynamic compression ratio, etc.
 

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2017 XT5
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The octane requirement has absolutely nothing to do with the engine displacement. It's all a matter of how the engine is designed and tuned - cam timing, spark timing, dynamic compression ratio, etc.
Yep. In fact, it's not really "octane" - it's the "octane rating", meaning it performs "as if" it has that much octane. The higher the octane rating, the higher the temperature required to cause combustion. Because of Boyle's Law, the more you compress something, the hotter it gets. High-compression engines tend to run hotter and can cause the air/fuel mixture to combust before the spark plug fires. A higher octane rating can prevent that.

Oddly enough, the XT5's V6 engine has a high compression ratio of 11.5:1, which would normally require a higher octane rating. Using technology like direct-injection, oil-spray piston cooling, and revised coolant passageways, temperatures in the combustion chambers are reduced so that higher octane fuel is not needed.
 

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'93 SedanDeville 60 Special
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Another part of the equation is most people to this day do not know, care or ask what they are pumping into the gas tank
Over 4 years ago the Feds allowed Ethanol grade of 15% added
Most people are not even looking at the pump or asking the station what is going out that pump E10 or E15 ?

So different answer is maybe regular with E10 OK but most GM owners manuals either were before E15 came out or
just do not mention E15
Regular with E15 is going to produce even less energy, run leaner, induce more engine knock which PCM then pulls more timing (reduced performance) out then E10 and would suggest going to mid grade gas if pumping in E15
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Most brand name gas stations here in the DelMarVa peninsula have pumps with stickers that state "May contain up to 10% Ethanol".

IIRC, that's also about the same from here to mid-Florida up and down I-95.

How does ethanol effect octane rating?
This is where ethanol comes in. In terms of its octane rating, ethanol has a rating of 113. ... When you mix 10 percent 113 octane ethanol with 85 octane gasoline it increases the octane two points to the normal 87 octane most consumers use. So the higher the ethanol content, the higher the octane.May 17, 2016
Ethanol and Octane For Beginners
Ethanol and Octane For Beginners

E15 has a higher octane rating than E10 but you need to burn more of it to make the same power output due to Ethanol having less heat output than gasoline, so - yes - an engine calibrated for E10 will seem to run a bit "lean" on E15.
 

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Hahahaha, love the Coke / water comparison. Only from a salesman. Means nothing otherwise. I put 87 in XT5 no probs and 92 in my CTS cause I love her more.
 

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561 Posts
Feds advanced a flurry of biofuel policy proposals last year, including plans that could help ethanol producers sell more of the corn-based fuel.

Final decisions about those possible changes to biofuel-blending mandates and warning labels at pumps dispensing higher-ethanol E15 gasoline will now fall to President-elect Joe Biden.
The Environmental Protection Agency’s proposals ensure the Biden administration will inherit battles over 16-year-old requirements to blend renewable fuels into gasoline and diesel that bedeviled President Donald Trump.

Under one of the EPA proposals advanced, the agency is seeking to modify or even completely scrap requirements for a warning sticker wherever pumps dispense the E15 gasoline blend containing 15% ethanol.

The current orange and black sticker cautions that E15 should only be used in passenger vehicles no older than 2001, and should not be used to fuel up boats or other gasoline-powered equipment because of the risk of damage and violating federal law.

Ethanol advocates say it discourages motorists from filling up with E15 and is no longer needed.
Ethanol producer POET LLC has encouraged label changes as one of several moves the Biden administration can take right away to make it easier to sell E15.
Even with the fact E15 runs like crap in cars like the Corvette and will do further fuel system damage

Warning Label

However, oil and refining leaders have insisted it is necessary to ensure the fuel isn’t pumped into equipment not certified to use it.
Some lawmakers have advanced legislation that would go in the other direction, roughly tripling the label’s size and explicitly adding the word “warning” to it

The EPA also is proposing changes that could make it easier to store higher ethanol blends in existing underground storage tanks that were not designed to support it

“We are pleased to see this first step toward removing onerous labeling and underground tank requirements and expanding access to E15 for American drivers,” said Emily Skor, chief executive of the pro-ethanol group Growth Energy.

“We look forward to working with the incoming Biden administration to ensure that the final rule addresses any remaining retail and infrastructure barriers that currently hold back cleaner, more affordable options at the fuel pump.”

Vehicle owners must then make sure what level of Ethanol they are pumping into their gas tanks,
and go to only gas stations that can clearly tell you if the pump has E10 or E15

Also need to know about even worre smog testing rules that will harm engine performance and doing mods

Tougher Smog testing
 

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Hopefully Biden will keep in mind his love for driving his green Corvette convertible and how it will run like s... with E15.

Problem is that Politicians follow the money.
 

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To make it worse when E15 was approved by the feds over 5 years ago they stated that testing of E15 be done and only used for vehicles newer then 2014 and that all pumps be labeled for E15
Then the feds stated no testing was done and be OK for vehicles 2001 and newer when GM themselves stated those older vehicles would not carry warranty damages if more then E10 was used.

I see this all the time in my work of tuning PCMs where vehicles run like crap and I test the fuel in tank to find without owners understanding are pumping in E15 and the engine performance is reduced as to more engine knock, misfires and PCM yanking out more Ign timing :(

Problem is that Politicians follow the money.
Was just another sneaky tactic to obtain peoples and companies votes from states profiting from Ethanol
 

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Before this thread turns into a political pissing contest, please keep to gasoline and facts - put the political innuendo in the correct Current Issues forum. Thanks.

Read the sticky intro first - Cadillac Owners Forum
 

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Just got my XT5 with the 3.6 on Saturday. The manual says gas with an octane rating of 87 (regular) is acceptable. The Cadillac salesmen said, "Yes, but..." Their explanation was that 87 is like Coke and 93 is like water. Your body will run on either one, but it will run better on water. Cadillac are like that in they will run on either but will run better on 93.

My wife's Escalade with the 6.2 says 93 is recommended but not required. However, it's a much larger engine. My intuition says GM probably uses the 3.6 in a lot of other applications all the way down to Chevys, so 87 is likely fine.

What's the general consensus on this?
Ran my XT5 on 87 got great mileage and never had a problem, I would say however if you do a lot of city stop and go driving stick with 93.
 

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That salesman's explanation has got to be one of the dumbest I've ever heard. 87 for your vehicle is fine. Some newer engines that recommend 87 can squeeze just a few more HP out of a higher octane fuel but it's really not worth it as I recall a recent study saying.
 

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You can use whichever you like, as long as you're consistent. As mentioned above, the primary difference is the temperature at which they burn. These modern engines will adjust the timing and fuel injection to match the fuel you're using. I would not however, recommend "using 87 normally but once in a while throw in 89 or 91" as this will introduce more anomalies, and make it more difficult for the computer to calculate accurately.
 
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