Christmas Road Trip results (87 octane vs 93)

[rudapa]

My only choices here are non ethanol 87 and 91 or 10% ethanol at 87, 89, and 93.(and E85 which I never use).

[RM4665]

So what does this definitely boil down to? If I put 91 or 93 in my truck instead of the 87, is it going to run better or get better mileage? Is it worth the added expense, maybe 5 or 6 bucks per tank?

[rudapa]

TBD, but probably no

[L-G]

Been running 87 in mine since new. Mpg has been around 17.5 or so even with the bigger coopers (haven't adjusted the speedo). Today was my first fill up with 93. I noticed about 20 miles later that it goes into v4 a tad easier but feels slightly more peppy ( but ugly when I am at moderate throttle).

 

More later.

[rudapa]

I'm going to try the 91 non ethanol next. I have to admit that the 93 ethanol test has been worthless. I've driven in 30 - 40 MPH head winds and sub zero temps, so nothing to really learn from this tank other than saying "she ain't getting good mileage" in head winds or low temps,

[SY2455]

Are you going to try the 93 ethanol test again later on when the wind calms down?

[waumo1]

The question earlier as to why GM markets a vehicle for 87 octane fuel if it will run better on higher octane fuel?

 

Simply because most people care nothing about performance and will not buy a vehicle if it says "Premium fuel required".

[seamonster]

You are right the premium required made me buy the 5.3 instead of the 6.2. However I will probably run

mid grade non ethanol in it. I have found I get at least 2 more MPG with the 89 non ethanol and at

20 cents more it is worth it to me. I dont think going to 91 with no ethanol for another 20 cents does me

any good it is the non ethanol that make the biggest difference. I just dont like the premium "required" part of the 6.2.

 

[Kuff]

the truck is designed to run in 87. Running 93 without a proper tune wont make a difference.

The mileage difference you are seeing is most likely attributed to difference in environmental changes. Aka, wind, temp, etc.

I have read somewhere that auto makers must allow the vehicle to run on 87 octane. Not sure if that is by law or what but... So yes, technically it is designed so it can run on 87, but in reality the engine will thrive on a high octane.

[Kuff]

Interesting!

 

Thus far, I've only run 2 full tanks of gas through my truck, and I'm sitting just over ~900kms (~600 miles) on the odometer. So far, the mileage technically SUCKS, however, it's got everything to do with the DAMN COLD WEATHER we've had ever since I picked up the truck 3 weeks ago! The truck has spent way more time sitting idling than I'd like (esp. for a new engine) but I'm not jumping into a freezing cold truck and driving away without letting it warm up.

 

After I ran the first tank empty, I switched to a 91 non-ethanol fuel to see if there would be a difference. It's honestly too early for me to tell. What I CAN TELL so far is that the outside temperature has a huge effect. Once it drops below the freezing mark, esp. by -5°C (25°F or so) the mileage falls off big time. We've had a couple days with the temp just above freezing, and I've been able to see the numbers improve A LOT (ie: 18 litres/100kms when it's bad, down to 13 litres/100kms when it's warmed up ................sorry CANADIAN mileage data, not MPG!!).

 

I'm curious to see how it performs when the weather warms up. I can see how it can easily get over 20 MPG if the conditions are right. It'll be easier to compare the difference between fuels then too.

 

Wow that is not the best mileage. Even with -15°C to -20°C I was averaging 13.5 L/100km. On days where it was -5°C I get down to about 12.5 L/100KM.

 

The few road trips I have taken I have averaged right around 10.5 L/100KM with my best 100KM being 8.9 L/100KM (was a bit 5 KM worth or so of downhill involved if I remember correctly).

[gtptyler]

Very interesting. will be doing some tests once we are above freezing.

 

Its like my gtp with the supercharger, it is recommended to run a premium fuel but can run a lower octane if needed but will have a lot of knock especially when in boost. It is very pronounced when I get a low octane or low quality fuel in there but throw premium in and runs like a dream. It always gets at least 91