Gas grade? Gmt 900 2011 5.3

joshw1303 · August 14, 2013

I've been reading a lot in new -gmt 1000 forum about how a lot of ppl are using mid grade 89 in their 5.3l. So I've been using 87grade from Shell or Petro Canada and didn't seem to have issues but at 40k I had the top engine redone to the new pistons and rings, etc under warranty due to cylinder deactivation. So should I be using 89 grade, does it help? Will the computer pick it up or will I just waste money?

Any help be appreciated.

Josh

Chris · August 14, 2013

Waste. Use 87 like your manual says. Then pick up the range afm delete plug-in or have it tuned out. The new direct injection engines require at least 89.

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Bad Bowtie2 · August 14, 2013

Just run pure 87 octane if you can get it. Adding a can of Chevron's Techron or a can of Sea Foam brand fuel treament at each oil change would also be a GREAT ideal.

joshw1303 · August 14, 2013

Just run pure 87 octane if you can get it. Adding a can of Chevron's Techron or a can of Sea Foam brand fuel treament at each oil change would also be a GREAT ideal.

I cannot find pure 87 grade, everything here is plus 10 percent ethanol.

Bad Bowtie2 · August 15, 2013

Then just stick with the name brand stations (Shell, Chevron, etc).

Add one of the two fuel treatments to your tank at each oil change interval, as mentioned above...

MikeNH · August 15, 2013

These trucks are flex fuel. The only benefit to ethanol-free is slightly better mileage. Just run name brand and you're gonna be fine.

Cowpie · August 24, 2013

Can't say if it is the same in Canada, but where I live, regular gas is around 87 octane and 10% ethanol is around 89 octane, and is also about 10 cents a gallon cheaper than regular. I just avoided all that and went with 105 octane rated E85 that is a dollar a gallon cheaper than regular in my area. Regular $3.46, E10 $3.36, E85 $2.39. No brainer. Even with the mpg loss by using E85, my cost per mile of operation is 3 cents a mile less than using regular gas.

montyss · August 24, 2013

best to use top tier as they have the recommended additives , in Canada the top tier stations are Shell , Esso , Petro Can and Chevron

http://www.toptiergas.com/retailers.html I also use the Chevron Techron Concentrate Plus at each oil change

Alex@BBP · August 24, 2013

We suggest to not use 87 octane under any circumstances, as it provides less power and worse fuel economy than 89 octane, even with the factory tuning. GM has designed that engine in such a way that a minimum of 89 octane and above is needed for best mileage and power output.

joshw1303 · August 24, 2013

We suggest to not use 87 octane under any circumstances, as it provides less power and worse fuel economy than 89 octane, even with the factory tuning. GM has designed that engine in such a way that a minimum of 89 octane and above is needed for best mileage and power output.

Wish I knew this sooner. I have been. Using 87 octane but she'll brand or Petro Canada. I couldn't find anywhere what octane to use. Thanks BPP. I'll start using 89 octane, I thought higher octane was for new 14s. Never knew my 2011 should be using 89 or higher.

MikeNH · August 25, 2013

We suggest to not use 87 octane under any circumstances, as it provides less power and worse fuel economy than 89 octane, even with the factory tuning. GM has designed that engine in such a way that a minimum of 89 octane and above is needed for best mileage and power output.

Wish I knew this sooner. I have been. Using 87 octane but she'll brand or Petro Canada. I couldn't find anywhere what octane to use. Thanks BPP. I'll start using 89 octane, I thought higher octane was for new 14s. Never knew my 2011 should be using 89 or higher.

GM recommends regular likely because the engine will still run acceptably and also because they don't want to lose ground to the other brands. Ram recommends mid grade in the 5.7 I think but Ford makes do with regular. But Blackbear has seen proven results with 89 and that's hard to argue.

joshw1303 · August 25, 2013

GM recommends regular likely because the engine will still run acceptably and also because they don't want to lose ground to the other brands. Ram recommends mid grade in the 5.7 I think but Ford makes do with regular. But Blackbear has seen proven results with 89 and that's hard to argue.

Yes, I agree and I just filled up with mid grade from Petro Canada.