My Results: 87 vs. 91 Octane

[caslerst]

So I'm sure this has been covered before but I just got the truck a few months ago and I was curious.

The truck is an '02 Sierra ECSB 4x4, 5.3, 3.73, auto, 265/75/r16, no lift, 77k on the clock. Only performance mod is a cat-back 3" single outlet Flowmaster.

All of these results are in Reno, NV (elevation 4800 to 5200) going to work and running errands on the weekends. It's about 15 miles to work, mostly freeway 65-70mph going in, and about half of it is stop and go on the way home. I tried my best to keep my driving habits the same but you can see the I was a little heavier in the foot when I first got the truck going from 15.5 to 16.3 mpg.

I started back in Feb. or so with 87 octane when the temp was peaking in the mid 40's and did 5 tanks. I then went to 91 octane on April 19th. Since then the weather has been in the mid 60's up to the mid 80's today. I used the A/C once with the 91 octane.

87 octane results
Miles Gallons MPG
311 20 15.55
224 14.2 15.77
340 21.7 15.67
290 18.61 15.58
383 23.5 16.3

two tanks with 91 octane
313 18.5 16.92
301 17.6 17.1

So that's an average of 15.77 on 87 octane and 17.01 on 91. So if 91 is 20 cents more, by my math every 1000 miles I would save $2.59!!!!

I did not notice any difference in power or throttle response or anything like that. But I've always been a "buy the cheapest you can" kind of guy. Maybe I'll have to change?

[04CHEVYYFZ]

great, I've never ran anything lower than 91 in my truck since I got it new off the lot. I just noticed on previous trucks that I always got better milage with premium.

[SnowRider1]

I am over in Spring Creek (Elko), and with my 04 it is about 1.5 mpg better with the 91. My last rig was 03 1500 Dodge with 360 and a/t, and it made no difference with 85, 87, or 91. But, when I filled it at the Chevron station,(with 91) it was almost 2 mpg better than with any other gas! I haven't checked the 04 lately, but in Feb., it got 17mpg to Vegas and back driving @70 mph.

[Whifflebat]

2 tanks on one octane and 5 on another isn't very good satisticallly.

[Joe]

2 tanks on one octane and 5 on another isn't very good satisticallly.

Running a higher octane then your motor is setup for give you nothing but a lighter wallet

[caslerst]

2 tanks on one octane and 5 on another isn't very good satisticallly.

True, but I was tired of waiting.

[Lochenjons]

always ran 87 on mine. heard the others wernt much of a difference.

[superx1965]

do u guys run a cooler thermostat when using ur hypertech? my truck already pings easily and i was thinking a cooler thermostat might help prevent it.