Best octane fuel for fuel eceonomy? (5.3L only)

[cfmistry]

I've searched and read many posts, but I'm looking for more peoples' experiences.

What octane gas yields you the best mpg in your Burb / Tahoe / Yukon? Which grades have you tried?

Please only respond if you have a the 5.3L since the 6.2L requires premium.

BlackBear recommends 89-octane due to the compression ratio of this engine. I've run both 87 and 89, but I'm not sure I ran 89 long enough to see the changes. Would you see them over 1 tank?

Thanks all!!

 

[GreyStone]

what does the owners manual recommend.

 

[cfmistry]

The owner's manual recommended a minimum of 87-octane. BlackBear performance is a pretty reputable company (especially on this board) that disputes that - they recommend 89 or higher.

 

[GreyStone]

you can most likely use either one as long as there is no pinging under load.

 

[Bob2C]

I have a tune (not BlackBear) on my 5.3 running 93 and get better MPG than stock on 87


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[wjburken]

Octane and the amount of energy in the fuel are two different things in my opinion. If I am not mistaken, Octane indicates how resistant the fuel is to premature detonation due to compression which is why the higher the Octane is, the less pinging you get. This is why higher compression motors, like the 6.2, need higher octane fuel. There is a small correlation between octane an mpg, but if you put 93 octane in a motor designed to run 87 octane, you won’t see a big change in mpg’s.

Typically, you will get better mileage with a furl that has less alcohol, but more power with more alcohol.

@swathdiver has a thread where he discusses this at length.
https://www.tahoeyukonforum.com/threads/useless-information.97483/page-85#post-1456757

 

[91RS]

If you're engine is stock and not tuned 87 is all you need. If you have a tune then you need to run whatever it has been tuned for be it 87, 89, or 93.

 

[intheburbs]

Trying to get better mileage by switching octane is a fool's errand.

The octane rating does not change the amount of energy in a gallon of gas. The octane rating is merely a quantifiable measure of how fast the fuel burns. Higher octane burns slower.

Any purported "increase" in mileage using a higher octane is easily offset by the higher cost, negating the benefit.

Never mind the fact that these things were/are built for a myriad of reasons, the least of which is economical use of fuel. Giant vehicle, horrible aerodynamics, large V8 engine. You want good mileage? Buy a Prius.

 

[K2 Kaiju]

...

 

[Foggy]

Totally agree with Texasdaddy above.
It's a waste to buy higher octane if your engine doesn't require it..
BUT, a company like Blackbear has tuned so many of these vehicles, that
they have probably seen that 87 octane, at certain loads, probably causes
the knock sensors to see knock - therefore reducing timing AND adding fuel....
because that's what the ECM does when there is detonation/pre-ignition to
save the engine from self destruction.
So ... if you run 89 OCTANE, you will stay out of those circumstances avoiding
the extra fuel rush and timing retard... You won't be able to hear it or notice it..
And that's the beauty of the modern engine and electronics
Run the 89.. esp now it's cheap and see if it helps with YOUR driving condtions
IF you are at say 1200 ft above sea level it may not make any difference.
But if you are at 200 ft and maybe your local gas isn't that great... you may be
adding a lot of life to your engine

 

[OR VietVet]

When I first got my Tahoe I ran just 87 octane. I already knew about advantages of higher octane when it comes to slower burning and helping with pinging. I ran shops, why wouldn't I.

I watched and monitored my MPG at all three octane levels. Only by a smidge, the 89 octane was better for me. I also know that the higher octane fuels have more additives that help keep fuel systems cleaner. I saw no advantage of premium fuel with my MPG. If I ran premium it would be solely for the additional additives it has over the mid grade. So, no matter what my experience is, I would run 89 octane based off the recommendation by BBP.

 

[George B]

I am about to do a real world test on this. I have attached the charts of my MPG and cost per mile for mixed city and highway driving. I have 93 non ethanol available locally so I am going to a couple tanks of that to compare.

 

[swathdiver]

I've searched and read many posts, but I'm looking for more peoples' experiences.

What octane gas yields you the best mpg in your Burb / Tahoe / Yukon? Which grades have you tried?

Please only respond if you have a the 5.3L since the 6.2L requires premium.

BlackBear recommends 89-octane due to the compression ratio of this engine. I've run both 87 and 89, but I'm not sure I ran 89 long enough to see the changes. Would you see them over 1 tank?

Thanks all!!

Cyrus, do you have ethanol available where you live? Where do you call home?

 

[cfmistry]

This is exactly the discussion I was looking for guys.

Unfortunately I do not have E-85 readily available near me (Maryland). Wish I did. Also because there are so few stations with it in my state the price is unreasonably high.

I will try running 89-octane for a few tanks and see how I do. Right now with 87-octane I am averaging 13.1mpg which is not great.

To those with the "it's a huge truck, why care about mileage" philosophy; I disagree with you entirely. I am not trying to save money - I am trying to increase range. Another 20 miles on a tank is a big difference to me. No need for a Prius, my good-mileage car is an E63 AMG that gets 17.1 mpg.

 

[George B]

This is exactly the discussion I was looking for guys.

Unfortunately I do not have E-85 readily available near me (Maryland). Wish I did. Also because there are so few stations with it in my state the price is unreasonably high.

I will try running 89-octane for a few tanks and see how I do. Right now with 87-octane I am averaging 13.1mpg which is not great.

To those with the "it's a huge truck, why care about mileage" philosophy; I disagree with you entirely. I am not trying to save money - I am trying to increase range. Another 20 miles on a tank is a big difference to me. No need for a Prius, my good-mileage car is an E63 AMG that gets 17.1 mpg.

I my average is 13.85 so I get about the same. Love how it runs on E85. But like you the price is too hight to make it worth it. I could do better by changing my driving habits but I like to put my foot in it.

 

[swathdiver]

This is exactly the discussion I was looking for guys.

Unfortunately I do not have E-85 readily available near me (Maryland).

I saw a Royal Farms in Millersville and a Liberty in Annapolis that have it.

Anyway, it's been my experience, no matter the car* driven, that running higher octane fuel in it results in greater efficiencies. I've been tracking my fuel economies since the 1980s in everything from Toyota Corollas to Buick Regals to F-SuperDuty trucks. The caveat is that these new direct injection engines burn everything with the same efficiency compared to conventional fuel injection or carbureted engines.

However, as some alluded to, even if Chevron's 93 delivers the highest MPG, the cost per mile may not make sense from an economy standpoint. Our old Pontiac Montana gets better mileage on 93 than 89 but it costs less to operate per mile on 89. Same for my daughter's little Kia. She gets more range from a tank of Mobil or Chevron 93 but it costs less per mile right now to burn 87. However, this has not always been the case, for the last ten years or so, it has cost us LESS per mile to run 93 than the lower grades of fuel when prices were much higher.

The fleet average for all years and models of the GMT-900 wagons was 14.3 MPG in 2018.

Mine has a three year average of 14.8 MPG @ twenty-one cents a mile on 93 octane gas. E25 delivers 14.7 MPG @ seventeen cents a mile. E20 delivers 15.4 MPG @ eighteen cents a mile.

Of course costs fluctuate and change over time so we use both metrics and weight the one that means more to us at a given time. Like you, when I want range, I don't care how much the fuel costs, I just want to get there without stopping!

In addition, good gas mileage is also a sign of the engine's health and efficiency of driving habits.

 

[Cpta88]

I have found I get about 150km a tank more if I run 89 or higher but I think it has more to do with ethanol content. Ethanol from what I understand is less efficient of a fuel than gasoline. Where I am 85 and 87 has up to 10% ethanol so I run 89 or 91 depending on the station. 94 didn’t notice any changes.

I also found pulling my travel trailer I get way better performance with the slightly higher octane and no ethanol.

I have a 2018 suburban with the 5.3

 

[1BADI5]

On E85 I avg 8.8 LOL

On 93 (i have a performance tune and 3.73s) I can get 18.5 mpgs mixed. I will be taking a roadtrip from near Annapolis, MD to Clarksville, TN the first week of August. So I will be curious to see what I get(730miles one way)

 

[intheburbs]

This is exactly the discussion I was looking for guys.

Unfortunately I do not have E-85 readily available near me (Maryland). Wish I did. Also because there are so few stations with it in my state the price is unreasonably high.

I will try running 89-octane for a few tanks and see how I do. Right now with 87-octane I am averaging 13.1mpg which is not great.

To those with the "it's a huge truck, why care about mileage" philosophy; I disagree with you entirely. I am not trying to save money - I am trying to increase range. Another 20 miles on a tank is a big difference to me. No need for a Prius, my good-mileage car is an E63 AMG that gets 17.1 mpg.

I guess I'm just not understanding. What, you live in such a remote area that you need that extra 20 miles of range? There are that few gas stations in your AO?

These trucks have 26-gallon tanks. Even with my Denali, at 12 mpg on premium, that's a 300-mile range. How could an extra 20 miles make even the slightest difference in anything?

Besides, if you had a 3/4-ton, you'd have a 39-gallon tank. My record is 586 miles on one tank. Without stopping.

 

[BG1988]

I've searched and read many posts, but I'm looking for more peoples' experiences.

What octane gas yields you the best mpg in your Burb / Tahoe / Yukon? Which grades have you tried?

Please only respond if you have a the 5.3L since the 6.2L requires premium.

BlackBear recommends 89-octane due to the compression ratio of this engine. I've run both 87 and 89, but I'm not sure I ran 89 long enough to see the changes. Would you see them over 1 tank?

Thanks all!!

Toyota Prius.