6.2l Octane Test On Fuel Economy

[jaybyrd]

Although I'm not too surprised for those who are not sure about the 6.2L and fuel economy here is my comparison between using regular 87 octane vs. 91 octane which I've been using for every tank except 2 for this comparison.

 

Both cases I drove back and forth to work averaging 90km/h (56 mph) driving exactly 100km per day using cruise control for 45 km each way of which is hwy.

 

87 octane

13.8L/100km or 17 mpg

Cost for 98L gas = $ 124.46 (full tank)

 

91 octane

12.4L/100km or 19 mpg

Cost for 98L gas = $ 134.26 (full tank)

 

Assuming 600 km per tank in each scenario for ease of comparison the premium fuel is $ 10.67 more for a tank; or essentially financially equal due to fuel economy differences.

 

$1.27/L 87 octane, $1.37/L 91 octane, and to put that in american so you see how much more we pay for gas North of the border that's equal to $4.80/USG and $5.19/USG respectively....

 

So given the better fuel economy with premium and the seemingly equal price due to better fuel economy with premium it is really a no brainer to use premium fuel with the 6.2L given the added performance as well. My experience is that this engine runs extremely well on premium as is recommended by GM and is super powerful. I therefore so no reason to ever use regular grade fuel unless the gap between regular and premium was to increase 3-4X.... But even then I'd still feed my baby the good stuff.

[cujo8]

So GM recommends 91 octane for the 6.2L Engines? I didn't know that.

 

Has anyone tried this experiment on a 5.3L engine? Maybe between 87 and 89 octane for example? I know GM recommends 87 octane for the 5.3L V8's, but was curious if anyone has tried this on their own truck.

[kdixer]

So GM recommends 91 octane for the 6.2L Engines? I didn't know that.

 

Has anyone tried this experiment on a 5.3L engine? Maybe between 87 and 89 octane for example? I know GM recommends 87 octane for the 5.3L V8's, but was curious if anyone has tried this on their own truck.

 

 

My 09 5.3 had significant spark knock running 87 with the factory tune. When I had Black Bear tune it he recomended to run at least 89. You can tell if you are getting nasty spark knock because the power will feel notchy. It will pull hard...feel flat...and pull hard again. That is because the ECM is pulling timing to eliminate spark knock when it detects it.

[Stevens03]

I run 89 in my 6.2L right now, and when I keep the speed 60mph or below, I easily pull 19mpg. Good results

[Baja 252]

Great info, thanks for taking the time to post it.

 

I have 15k on my 6.2 and I usually use 87 octane. That however will all change tomorrow, Justin is tuning my truck at 9:30 in the morning.

[Stevens03]

Great info, thanks for taking the time to post it.

 

I have 15k on my 6.2 and I usually use 87 octane. That however will all change tomorrow, Justin is tuning my truck at 9:30 in the morning.

 

Post results.... I'm getting mine done May 14th

[ChevyTech77]

So GM recommends 91 octane for the 6.2L Engines? I didn't know that.

 

Yes. 10.5:1 cr with a fairly aggressive camshaft profile = premium fuel.

[MaverickZ71]

So GM recommends 91 octane for the 6.2L Engines? I didn't know that.

 

Has anyone tried this experiment on a 5.3L engine? Maybe between 87 and 89 octane for example? I know GM recommends 87 octane for the 5.3L V8's, but was curious if anyone has tried this on their own truck.

 

I haven't done a formal experiment like the OP, but I do know that on my factory-tune stock '09 5.3, it will ping very slightly on some 87 octane fuel. Since I switched to BP Silver (89 octane), it seems to run better, have more power, and it gets about 1+ mpg more on the average. I think it stays in 4cyl mode in the AFM longer because of the better fuel. Of course, like they say, YMMV.

[20Silverado11]

This is great information. Your truck appears identical to mine (including the color), so it's reasonable to assume my results would be similar. I had been toying with the idea of running regular for normal use and premium for towing - now I'll just go premium for all uses. My next items up for consideration will be Costco premium fuel + semi-annual Techron treatment vs. Chevron premium (looking at cost), and Black Bear tune vs. Stock (looking at MPG). Thanks much for the great post - I've learned something here today!

[HawkScot]

We did this experiment with our 2008 GMC Yukon XL Denali with the 6.2l and it was cheaper by a few bucks each tank to run premium. It had better performance also, but it did not knock or run bad on regular, just did not get the mpgs.

 

As for Costco gas, it did not like that at all, regular or premium. the mileage was down for both. We run Costco in some of our vehicles but not Denali (since traded) or the new truck (even though it has the 6.0 and runs regular).

 

With a blackbear tune, I would expect good mileage and even better performance on premium.

[ChevyTech77]

I have found huge increases, in just everyday driveability, from my old '98 5.7R engine by just running Shell 87 octane. GM has stated for some time that top tier fuels will promote better engine driveability and I found that it definently works for my old truck.

[RyanbabZ71]

With a blackbear tune, I would expect good mileage and even better performance on premium

 

Not the milage, the increase in performance ruins this You wont drive the same or slower with a tune.

 

I have been doing a comparison of 2 different types of E85. In both of my vehicles (5.3 and 6.2) I get worse milage with Meijer E85. I get better mpg with Gas America (2 mpg more on my Tahoe and about 1 on my truck)

[ChevyTech77]

E85 will always net worse fuel mileage. The engine must burn more of it to make the same "power" as it does with gasoline.

[temmert1]

I have run both in my 6.2L.....It definately runs better on 91. I especially notice it at lower rpm's. Let say 1,100 to 1,500 range, almost feels like its hesitating or missing on 87. I normally run Sunoco fuel.......Just made a 330 mile round trip from Watsontown Pa to Indiana Pa. I got 17.5 on the way there and 18.2 on the return trip running 87..... Going to switch back to 91 for good especially if I can makethe trip to Pittsburgh on May 14th to get a BB tune.....

[Stevens03]

I have run both in my 6.2L.....It definately runs better on 91. I especially notice it at lower rpm's. Let say 1,100 to 1,500 range, almost feels like its hesitating or missing on 87. I normally run Sunoco fuel.......Just made a 330 mile round trip from Watsontown Pa to Indiana Pa. I got 17.5 on the way there and 18.2 on the return trip running 87..... Going to switch back to 91 for good especially if I can makethe trip to Pittsburgh on May 14th to get a BB tune.....

 

Don't say if... DO IT!