2014+ Gas Mileage (MPG) Topic

johnnymordoc · June 19, 2020

Thanks Gentlemen - do we think it is the dirty injectors?

I can start running some Chevron though my tank every once in a while - out here in CA it is about +.30 more a gallon.

I guess you get what you pay for?

On the additives - is there any GM factory version?

If I have it done at the dealer during a maintenance - what are they going to do? Same thing? Pour something into the tank?

Thanks in advance.

JJ

DustinZ71 · June 25, 2020

On 6/19/2020 at 9:10 AM, johnnymordoc said:

Thanks Gentlemen - do we think it is the dirty injectors?

I can start running some Chevron though my tank every once in a while - out here in CA it is about +.30 more a gallon.

I guess you get what you pay for?

On the additives - is there any GM factory version?

If I have it done at the dealer during a maintenance - what are they going to do? Same thing? Pour something into the tank?

Thanks in advance.

JJ

I have used the BG 44k in the past and it seemed to work well. You just pour it into a full tank of gas and run the entire tank.

https://www.bgprod.com/catalog/gasoline-fuel-system/bg-44k-fuel-system-cleaner/

Skytrekin · July 17, 2020

Hello,

I have a 2016 GMC Sierra SLT 4x4 crew cab w/ 5.3 I just turned 45,000 miles and started changing out fluids. So far I have changed front and rear diff fluid and transfer case fluid as those are the easiest for me to perform. I went to the dealer and got the fluids, so all GM product. I changed the transfer case fluid first since it was the easiest. 2 plugs that are easy to get to.

On the fuel mileage screen I have seen an increase in MPG in city driving and now curious with the diff fluids changed how much more it might go up. The front was definitely dirty looking compared to the rear. Neither plugs had much crud on the magnetic plugs. The transfer case was pretty typical with a bunch on it.

Appointment next week at the dealer to perform the transmission service, they quoted $290 That is worth it to me to not mess with the exhaust pipe and getting the fill correct. They also told me it is a complete flush so I felt good about that.

Any way just wanted to chime in about normal service and improvement in MPG I was about 14-15 in town and its now around 17-18. Might not be accurate, but the feel good for keeping up on maint. is there

emaxxer86 · August 3, 2020

I cannot believe the mileage some of you are getting. I have a 2017 crew cab, 5.3, 4x4 with max trailering package and 3:73 gears. I was struggling to get 14-15 mpg on stock size tires. I just put LT275/70/R18’s on my truck, and I’m getting closer to 12-13 mpg. I’m driving like a grandpa! This mileage included was before I installed my new tires. This is one thirsty truck.

You need a tune.

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emaxxer86 · August 3, 2020

Yeah, that is what my MPG looks like. The more miles I put on the worse it gets. I blew $220.00 letting them put chemicals in manifold to get deposits off. Did not work. Waste of money. Looking for someone to blast it with walnut shells. Otherwise, I am trading it and going to a Ram port injection e-torque engine.

The Buildup wont happen if you block off the pcv system and vent the valve covers to atmosphere rather than run that crap back into the intake. I have the DOD disabled in my tune and gas mileage averages around 22+mpg at 75mph. I have 31.5” tires and 3.73 gears 4x4 double cab.

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lucas287 · October 13, 2020

Just browsing through this thread a little and it's crazy that the 6.2 gets pretty much the same fuel economy as the 5.3. 65 more HP, 80 more TQ and negligible difference in fuel economy. What's not to love??

I drive aggressive and usually on an ethanol blend ranging from E30 to E80 and my lifetime average since ownership (7,500 miles) is 17.6 mpg. On straight highway trips with E10 I easily nail down 22-23. AFM disabled too.

pokismoki · October 2, 2021

6.2 is the way to go.

short bed standard cab v6 is also a good combo it makes 300hp and gets over 18/24mpg

16LT4 · November 14, 2021

Now that the cold weather is upon me, and E85 shot up a dollar/gallon in the last week, it's time to switch back to E10; I don't like stressing the starter on prolonged E85 starts once the temperature dips below 50*F. My regular commute with several stop signs and a half dozen lights coupled with no sustained cruises longer than a few miles saw in the low 12mpgs on E85 during the last couple of months; it is hardly scientific, but with 89 octane (with the tank being E27 from residual fuel on today's fill-up), my trip MPG (reset at every fill-up) went from 12.5 to 15.1 after 11 miles, which consists of driving the same roads I always do. Lifetime fuel efficiency has dropped to 28.7 mpg from 30.7 mpg over the last few months of E85 commutes and short-distance towing/hauling.

mikeyk101 · November 14, 2021

3 minutes ago, 16LT4 said:

Now that the cold weather is upon me, and E85 shot up a dollar/gallon in the last week, it's time to switch back to E10; I don't like stressing the starter on prolonged E85 starts once the temperature dips below 50*F. My regular commute with several stop signs and a half dozen lights coupled with no sustained cruises longer than a few miles saw in the low 12mpgs on E85 during the last couple of months; it is hardly scientific, but with 89 octane (with the tank being E27 from residual fuel on today's fill-up), my trip MPG (reset at every fill-up) went from 12.5 to 15.1 after 11 miles, which consists of driving the same roads I always do. Lifetime fuel efficiency has dropped to 28.7 mpg from 30.7 mpg over the last few months of E85 commutes and short-distance towing/hauling.

Everything is a tradeoff. The E85 has traditionally cost less than E10 but also gives you reduced mpg. I guess the bottom line is if to see if you can end up traveling farther for less overall with the E85. I never could run E85 so never looked into that. I wasn't aware of the harder starting on E85 either.

16LT4 · November 14, 2021

9 minutes ago, mikeyk101 said:

Everything is a tradeoff. The E85 has traditionally cost less than E10 but also gives you reduced mpg. I guess the bottom line is if to see if you can end up traveling farther for less overall with the E85. I never could run E85 so never looked into that. I wasn't aware of the harder starting on E85 either.

Yes it is. A tank of E85 would last 300 miles, E10 would go 400 miles over the same commutes, but the cost/mile on E85 was still less when I was filling up E85 for half the price over the summer. Now with E85 being more expensive than 87, I'm not going to pay more for less mileage.

scrapen · March 19, 2022

Just returned to OH from FL, so I was able to get my first E30ish mix all highway. It was a very impressive 19.2 mpg (computer readout 20.8) considering it was through VA and WV, with some windy mountain road drives visiting parks. According to my scanner, it was 25% ethanol.

My previous tank from SC to NC was 20.9 MPG on 93 (computer readout 22.3). One before that was 19.6 (20.7)

Majority of the trip had cruise control set to 70 (or 5 over lower posted limit (i.e 60 in a 55).

I've recorded almost every fillup since 2019. I typically average 16-18mpg since i'm never taking big trips. I've only recorded 4-5 tanks where i only used E85. I've had about 10 tanks or so where I mixed fuel. Most of my tanks are still with 92/93 octane as I usually always have free fuel saved up through my local grocery store.

e15-e55 (most of these are e29-e34): 16.8 MPG

e55-e85 (i have not filled up only e85 since buying my scanner to test actual ethanol content): 14.6 MPG

E10 or less: 18.27 MPG

On average my e85 tanks save me 31% vs 93.

My mixes saved an average of 28% (typically 7-8 gallons of e85 with the rest 87)

As you can see my mpg only takes a 10% hit while saving 30% in my wallet. I should note that i have a tune on my truck for 91 and added the ethanol sensor for e85.

For you guys that use 87 everyday, this would be about a 5% savings in your pocket. Your mileage may vary as pricing fluctuates between brands and location. One state may have e85 1 dollar cheaper than 93 and the next only .75.

Edited March 19, 2022 by scrapen

lucas287 · March 19, 2022

2 hours ago, scrapen said:

As you can see my mpg only takes a 10% hit while saving 30% in my wallet. I should note that i have a tune on my truck for 91 and added the ethanol sensor for e85.

For you guys that use 87 everyday, this would be about a 5% savings in your pocket. Your mileage may vary as pricing fluctuates between brands and location. One state may have e85 1 dollar cheaper than 93 and the next only .75

Are your flex fuel tables actually active? If they aren't then you're running lean and over-advanced. Not a bad thing necessarily, but a possible explanation for your increase in fuel mileage.

Properly tuned, e30 stoich is about 13:1 afr - stock tune is hard-coded to 14.1:1 regardless of the fuel used, even if you simply plug an alcohol sensor in. And at e30 and properly tuned you'd probably be running about 2 less degrees of advance on the highway.

scrapen · March 20, 2022

Yes, Blackbear sent me a new tune file after i installed the sensor.

As for mileage "increases" I should note most of my miles are in-town driving which really brings down my averages. I typically only drive my truck when the little one needs to go somewhere or visiting family 15 miles away. When i unfortunately have to take the truck on a family excursion for the wife (4 adults and camping gear) i really like to see what mpg's look like highway only vs my normal around town driving. I posted in this thread the results of my last mostly highway trip to TN a couple years back where I ran only E85 to get there and only premium on the way back. This was before I knew about car studies on ethanol mixtures and the push for E30 gasoline in the future.

My car is the same way when it comes to mileage. I only get 600 miles to a tank driving to work every day (<3 miles)...but last year I made it halfway through Maine (818 miles) on 15.2 gallons.

Edited March 20, 2022 by scrapen

16LT4 · March 21, 2022

With warmed temperatures, I'm back to E85. By me, 93 is pegging $5/gallon, 87 is $4.40/gallon, and E85 is... $2.79/gallon. The Silverado has become the fuel-cost saver on my commutes (up to 200 miles each way) compared to my 93-burning E83. Yesterday's return mileage on E85 sucked because traffic added an hour to my drive; stop-go highway 0-70mph fluctuations kept my mileage in the 16s. Steady cruising at 68 at the beginning of the trip though, had my mileage continuing to rise into the upper teens until NYC happened. This afternoon I'll be data-logging mileage and cost to compare to the E83 to figure out actual dollars saved.

Edited March 21, 2022 by 16LT4

Grumpy Bear · March 21, 2022

1 hour ago, 16LT4 said:

With warmed temperatures, I'm back to E85. By me, 93 is pegging $5/gallon, 87 is $4.40/gallon, and E85 is... $2.79/gallon. The Silverado has become the fuel-cost saver on my commutes (up to 200 miles each way) compared to my 93-burning E83. Yesterday's return mileage on E85 sucked because traffic added an hour to my drive; stop-go highway 0-70mph fluctuations kept my mileage in the 16s. Steady cruising at 68 at the beginning of the trip though, had my mileage continuing to rise into the upper teens until NYC happened. This afternoon I'll be data-logging mileage and cost to compare to the E83 to figure out actual dollars saved.

All one has to do is get near a city and a hole opens in the gas tank :crackup: