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2011SRX,2015ATS RWD base 2.0
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Its 45-50 cents at my local Costco 93 octane in South Jersey, I have 65k in 52 months 95% Hyway [65-75 avg] lifetime avg 30.2 have never seen more than 32.5 on any fillup 13-15 gal this is a 2015 base RWD 2.0T 3375 curb wt. You will see a substantial fall off with mostly local driving, just saying.
 

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2013 ESV Platinum
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1 Posts
We use premium in all of our cars, the 6.2 V8 Escalade and G8, the 2.0T I4 ATS, even my old '96 V6 Maxima whose fuel door says "Premium fuel recommended for maximum performance". All of our cars average right at the manufacturers' advertised MPG numbers. I've never considered putting 87 in any of them, so I can't speak to the difference in fuel mileage. But I can say I am happy with the fuel mileage and performance I get out of premium fuel.
 

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2017 ATS-V Sedan, Vector Blue/Black, 6MT
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994 Posts
The 3.6 V6 used in every Cadillac except the XT4 and the Escalade is naturally aspirated and Direct Injected. That allows it to run a high compression ratio of 12.5 while using REGULAR GAS. Regular is the grade that is recommended for this engine, and there is NO benefit whatsoever from using a higher octane gasoline with this ubiquitous engine. The 3.6 turbo in the CTS V Sport and the XTS V Sport does require Premium, as does the 3.6 TT in my ATS-V. Premium is REQUIRED in these high performance engines (also the 3.0 TT in the CT6, I believe, as well as the monster in the CTS-V). Under most circumstances, regular can be used in those engines without damage, but they won't run nearly as well. In some circumstances, like full throttle and full boost in hot weather, there might be damage though, as the ECM might not be able to retard the timing enough to prevent bad pinging. The 2.0 in the XT4 produces significantly less power and torque than the previous 2.0 T used in the ATS, CTS, and the CT6, so probably uses less boost, and could be more tolerant of regular gas than the old 2.0. But it will still make more power and get better mileage with Premium, even if only by a few percent. As I've stated before, the difference will be most noticeable in hot weather or when towing, and there may be no difference at all in cold weather.

Of interest, back in the late 90's I had a 993 Porsche Targa. The only dealer in Atlanta at the time was a separate dealership and building, but it was next to their Chevy dealership, and the shared the gas pump, which was REGULAR ONLY. Premium was required in these cars, of course. I hated when they did me a " favor" by filling up my tank, because my car could barely reverse up an incline with regular, and would frequently stall. No problems with Premium, of course. Once I got to drive a 993 twin turbo demo, and it would only do 0.7 bar of boost with the crap regular in the tank. It would do 1.0 all day long with premium. No pinging, but a noticeable loss in performance. Again, premium was required in these cars.
 

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2019 XT4 SPORT
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20 Posts
Discussion Starter #27
I am running my tank to empty (filled with regular) as we speak and will do a Premium fill to see if I notice any difference. I will report back.
 

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2019 XT4 Premium Luxury FWD
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134 Posts
The manual for my 2019 XT4 specifically says,
"Premium unleaded gasoline meeting ASTM spec D4814 with a posted octane of 93 is highly recommended for best performance and fuel economy."

It goes on to say "unleaded gasoline with an octane rating as low as 87 can be used. Using octane below 93 will lead to reduced acceleration and fuel economy. If knocking occurs use a 93 octane as soon as possible otherwise the engine could be damaged.

91 octane called mid grade is sold here and I've been using it with no problems.
 

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2010 CTS 3.6L V6 RWD Performance
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187 Posts
The manual for my 2019 XT4 specifically says,
"Premium unleaded gasoline meeting ASTM spec D4814 with a posted octane of 93 is highly recommended for best performance and fuel economy."

It goes on to say "unleaded gasoline with an octane rating as low as 87 can be used. Using octane below 93 will lead to reduced acceleration and fuel economy. If knocking occurs use a 93 octane as soon as possible otherwise the engine could be damaged.

91 octane called mid grade is sold here and I've been using it with no problems.
This makes sense. If GM makes a car that requires premium fuel or else big problems, then they can they can just forget about the entire market for rental cars for that model. For example, I've rented a VW Golf from Hertz several times at airports and they have the same recommendations about premium fuel. I've filled them with regular and didn't notice any difference. I want to save as much as possible on gas because it gets charged to a project budget in the company. I'm sure that most everybody else does that with airport rental vehicles also. I'm sure that Hertz knows their fleets and how much abuse they can handle.
 

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2019 XT4 Sport AWD - Crystal White / Jet Black
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102 Posts
Is 91 octane better than 87 or 89 for this engine?

93 is harder to find where I live where most stations have 91 as the highest octane gas. There are a few with 94 but not conveniently located.

I have been using 91 since first fill up (doubtful the first tank dealer provided was anything better than regular :)). Just wondering if 91 would be good enough?

Thanks.
 

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XT4 RED SPORT
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2,387 Posts
Is 91 octane better than 87 or 89 for this engine?

93 is harder to find where I live where most stations have 91 as the highest octane gas. There are a few with 94 but not conveniently located.

I have been using 91 since first fill up (doubtful the first tank dealer provided was anything better than regular :)). Just wondering if 91 would be good enough?

Thanks.
Me personally I would think that 91 Octane would be very OK to use. (Yes 91 is better than 87 or 89) You may want to try a tank of both 91 & 93/94 to see if you notice any differences.
 

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2019 XT4 Premium Luxury FWD
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134 Posts
Correction to my post #28. I said I used 91 octane but in fact I filled up with 89. There is no 91 here. Premium is 93 and about .40 more than 89.

What I do is blend my fill ups. I just filled up with premium and next time I will use midgrade. I know it isn't much but every little bit helps in the long run. I see no performance or knocking issues. Also, I try to use Shell when possible a top tier gas.
 

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2019 XT4 Sport AWD - Crystal White / Jet Black
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102 Posts
Me personally I would think that 91 Octane would be very OK to use. (Yes 91 is better than 87 or 89) You may want to try a tank of both 91 & 93/94 to see if you notice any differences.
Thanks, Marc.

Will try and compare 91 with 94 to see any difference, if any in performance and/or fuel economy.
 

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2013 XTS Premium in Silver Coast Metallic
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674 Posts
What's the point or benefit of using a Top Tier gas in a direct injection engine where the gas is directly injected into the combustion chamber and not sprayed across the intake valves, thus cleaning them, as in a port injected engine? Direct injection engines are well know for carbon buildup on the valves, causing rough idle, etc. A Top Tier gas, or using any kind of aftermarket detergent fuel additive will do nothing to correct that condition.
 

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XT4 RED SPORT
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2,387 Posts
Thanks, Marc.

Will try and compare 91 with 94 to see any difference, if any in performance and/or fuel economy.
Okay, now after driving my first FULL week and one FULL tank of gas I calculated the costs difference by using Premium gasoline.

We all know that the manual states that it is "Recommended" to use Premium fuel. and we all know that once in awhile you can use regular gas. Here is what I calculated the actual added costs for me are, where premium gas in my area is only .30 cents a gallon more.

I filled up with the (Low Fuel light on) and I pumped in 14 gallons of premium gas... so then at .30 x 14 gal. = $4.20 wk X 52 = $218.40 a year. So is spending approx. $218.40 a year more for better performance and better gas mileage, of course there will be more costs if you have added trips or vacations, but for the most part the average weekly driving cost of $4.20 worth the added expense??

Answer for me is a resounding YES!
 

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2019 Red XT4
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113 Posts
It all comes down to the extra fuel mileage you gain with the Premium VS the cost. Where I live in SW Florida, there is an approx. 40 to 50 cents per gallon difference. That's approx. 6 bucks per tank. In my estimation (non-scientific, of course) that is pretty much a "wash". At $6 more per tank full of Premium, that is about 2.5 gallons of regular gas, which equates to around 55 miles per tank, based on 22 MPG.
Are the Premium supporters getting more that 55 miles extra per tank?

Just curious.

BTW... I've only owned my XT4 for only a month now and only filled it up twice. Used Premium both times but still wondering if I need to. Still concerned about that "recommended" statement in the manual.
My 2019 Corvette Grand Sport requires the Premium and that I can understand!
 

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If it doesn't ping you don't need premium.
Yes, that is an option one can choose ... but you will notice reduced gas mileage and poorer performance with regular gas.

IMO: Saving a few dollars a week to get diminished results isn't really worth it to me.
 

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2019 XT4 SPORT
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20 Posts
Discussion Starter #40
I am running my tank to empty (filled with regular) as we speak and will do a Premium fill to see if I notice any difference. I will report back.
I am a low mileage guy. I have filled up three times since my last post both from empty. The first tank I filled with Mobil 93 and did not notice much difference I was averaging 18MPG in all city stop and go traffic. I switched to Marathon 93 and mileage boosted to 20 and car ran smoother. I pay particular attention to auto stop and it is definitely a cleaner start with a smoother idle. I am now convinced that Mobil gas I used was not 93. So in summary I will be using premium from now on. Difference is regular $2.80 to premium $3.30 mid grade is $3.10.
 
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