10,000 kms on 4.3 V6

Sean Demura · May 31, 2016

If I were a bit kinder to my gas pedal I'd probably get better mpg, but I'm averaging 18.5 combined right now. (2/3 city, 1/3 highway roughly)

tmo · June 1, 2016

It sounds to me like there is something wrong with your truck if it is getting 16 mpg. Are your tires oversized? Is your odometer reading kilometers instead of miles? Also, I thought all 4.3's came with the 3.42 rear end.

Yeah there defiantly is. I called the dealership a few months back to see about it and they said there was nothing they could do. And I don't have the 3.42 gears because my truck is not 4x4. All the 2wd have 3.23 (not 3.22). At least thats what the owners manual states. I don't have oversized tires only 20 inch stock rims and the stock tire size, but they are AT.

Are those numbers the numbers in the DIC? Mine reads 18 but I have never gotten over 16.8 and that was taking it super easy on the pedal.

Donstar · June 1, 2016

Yeah there defiantly is. I called the dealership a few months back to see about it and they said there was nothing they could do. And I don't have the 3.42 gears because my truck is not 4x4. All the 2wd have 3.23 (not 3.22). At least thats what the owners manual states. I don't have oversized tires only 20 inch stock rims and the stock tire size, but they are AT.

Are those numbers the numbers in the DIC? Mine reads 18 but I have never gotten over 16.8 and that was taking it super easy on the pedal.

I'm not sure if I understand your question correctly, but hopefully I can answer. Your DIC will read average fuel economy in either miles per gallon or litres per 100 kilometers. These are quite different methods. I do think you'd notice if you truck was set to the metric scale as your speedometer would be considerably different. (When you are driving 50 mph, your speedometer would read 80!)

Have you tried calculating your fuel economy by tracking your distance travelled for the amount of fuel you put in your tank?

tmo · June 2, 2016

I'm not sure if I understand your question correctly, but hopefully I can answer. Your DIC will read average fuel economy in either miles per gallon or litres per 100 kilometers. These are quite different methods. I do think you'd notice if you truck was set to the metric scale as your speedometer would be considerably different. (When you are driving 50 mph, your speedometer would read 80!)

Have you tried calculating your fuel economy by tracking your distance travelled for the amount of fuel you put in your tank?

Sorry that question was for the MPG's not the metric conversion, sorry for the confusion. Yeah mine is in the US measurements for sure. The Average Economy screen reads for me 16-18 MPG, but I never get over 16.8. That number is calculated by tracking distance and filling up at the same pump and then dividing it out. And I did change the truck to metric yesterday to see what the Average Eco. screen said and it was at 14.2L per 100 kilometers.

Donstar · June 2, 2016

Sorry that question was for the MPG's not the metric conversion, sorry for the confusion. Yeah mine is in the US measurements for sure. The Average Economy screen reads for me 16-18 MPG, but I never get over 16.8. That number is calculated by tracking distance and filling up at the same pump and then dividing it out. And I did change the truck to metric yesterday to see what the Average Eco. screen said and it was at 14.2L per 100 kilometers.

I switched mine to US yesterday and it read 21 mpg. However, I just did a 110 km trip on the highway, with some stop and go driving. I would find 14.2L per 100 kms very reasonable for around town driving. (I'm usually 15+)

mookdoc6 · June 2, 2016

I just drove 1800 miles on Chryslers 300C brand new with ZF 8speed over the Holiday. Went home and drove my brand new 2016 GMC with 8L90 8speed.

The ZF is good although when mashed in large grades and take foot off accelerators and mash the pedal again it does start to show it's confusion more than once. It was a pentastar V6 and the shifting was rolling off into the next gear looking for MPG gains. I did like it and it had not bothered me to say the least I was impressed.

Got home and drove my GMC 2500 miles on Odometer. The shifting for a Full size truck is actually quicker than the ZF it does not exhibit it's confusion at all on grades when being mashed and let of etc. The shifting is actually in my opinion quieter and smoother than the ZF which is in a car. I was not expecting this really to come home and find this new GM tranny being more refined than the ZF in a car.

Note: I have settled in nicely at 2500 miles and man it's butter now! Like I said, I am surprised it's actually better than the ZF in car platform?

Brian S. · June 5, 2016

I drove the 4.3l/3.42 for a year and got 17.4 overall, my first year with the 5.3l has me at 16mpg overall.

I haven't noticed a lot of difference between the two.

tmo · June 6, 2016

I drove the 4.3l/3.42 for a year and got 17.4 overall, my first year with the 5.3l has me at 16mpg overall.

I haven't noticed a lot of difference between the two.

I wish I would have gone with the 5.3. Even though most are getting only 16, I would have at least had the ability to say, "It's a v8 what do you expect." I pulled my first trailer today, DIC read 12 MPG. (the trailer was 1500-2000 pounds as it only had a gate on it)

I switched mine to US yesterday and it read 21 mpg. However, I just did a 110 km trip on the highway, with some stop and go driving. I would find 14.2L per 100 kms very reasonable for around town driving. (I'm usually 15+)

Yeah its not bad for town driving... but thats my highway driving most of the time. Haha

I'm probably going to have the dealership re-flash it like they said they would do a few months ago... its just a pain to take it in.

Brian S. · June 6, 2016

I wish I would have gone with the 5.3. Even though most are getting only 16, I would have at least had the ability to say, "It's a v8 what do you expect." I pulled my first trailer today, DIC read 12 MPG. (the trailer was 1500-2000 pounds as it only had a gate on it)

Wish no more my friend.

1. I get 12 mpg towing my 2500lb boat with the 5.3, and I did with the 4.3l as well. (double cab, 3.42, 4wd on both)

2. Passing a guy towing Memorial Day weekend with the 5.3l was pretty lethargic.

3. My teenager drives a 6 cylinder sports coupe, says making the 5.3l move is like "kicking an elephant in the butt". (and that's comparing to a six cylinder)

4. I think the 4.3l on E85 felt snappier than my non flex fuel 5.3l on anything.

The 4.3l is a good engine, my only problem with it was no external transmission oil cooler. (and people shocked I had bought a 6 cylinder truck) Dealer offered me a deal where I swapped trucks and added a year of payments after a year of use.

1500s are heavy vehicles, IMHO either the 5.3l or 4.3l move them about the same with stock tune anyway.

tmo · June 6, 2016

Wish no more my friend.

1. I get 12 mpg towing my 2500lb boat with the 5.3, and I did with the 4.3l as well. (double cab, 3.42, 4wd on both)

2. Passing a guy towing Memorial Day weekend with the 5.3l was pretty lethargic.

3. My teenager drives a 6 cylinder sports coupe, says making the 5.3l move is like "kicking an elephant in the butt". (and that's comparing to a six cylinder)

4. I think the 4.3l on E85 felt snappier than my non flex fuel 5.3l on anything.

The 4.3l is a good engine, my only problem with it was no external transmission oil cooler. (and people shocked I had bought a 6 cylinder truck) Dealer offered me a deal where I swapped trucks and added a year of payments after a year of use.

1500s are heavy vehicles, IMHO either the 5.3l or 4.3l move them about the same with stock tune anyway.

I'm actually very impressed with how the 4.3l pulled yesterday. I did not even realize I had a trailer behind me at times, other than the lower shifting up hills. I need to try the E85 gas again I think. I tried it once, but I'm not crazy about paying same price for gas to get lower mileage.

How does the 4.3l do on long trips when pulling a trailer. The trip yesterday was only like 10 miles one way and then back, but I have a trip coming up in July where I will be pulling an approx 2000 pound boat for 3 hours one way.

Thanks for the reply!

Brian S. · June 6, 2016

I'm actually very impressed with how the 4.3l pulled yesterday. I did not even realize I had a trailer behind me at times, other than the lower shifting up hills. I need to try the E85 gas again I think. I tried it once, but I'm not crazy about paying same price for gas to get lower mileage.

How does the 4.3l do on long trips when pulling a trailer. The trip yesterday was only like 10 miles one way and then back, but I have a trip coming up in July where I will be pulling an approx 2000 pound boat for 3 hours one way.

Thanks for the reply!

You won't have any problem.

My boat is a 17'8" aluminum deep V with a 150hp 4 stroke motor on it and I pulled it many times for an hour with the 4.3l and 3-4X for three to four hours.

It wasn't great for passing, but neither is the 5.3l. (nor were my previous 2002, 2005, and 2010 5.3ls)

Don't use thee E85 for towing- for me the mileage on E85 was around 8 mpg- not worth it.

The 4.3l definitely has the power to pull your boat, and the other weekend warrior type stuff you mainly see on the highway.

tmo · June 9, 2016

You won't have any problem.

My boat is a 17'8" aluminum deep V with a 150hp 4 stroke motor on it and I pulled it many times for an hour with the 4.3l and 3-4X for three to four hours.

It wasn't great for passing, but neither is the 5.3l. (nor were my previous 2002, 2005, and 2010 5.3ls)

Don't use thee E85 for towing- for me the mileage on E85 was around 8 mpg- not worth it.

The 4.3l definitely has the power to pull your boat, and the other weekend warrior type stuff you mainly see on the highway.

Thanks for the reply! I went all over town looking for E85 gas and found none. The only place I can find it is in Houston, and I'm not driving an hour into Houston to get it just to see how my truck runs on it. The last time I had it, the truck had half a tank of regular, so I didn't get the full experience, but I defiantly noticed a difference.

I did notice when I pulled out in front of a car (that was turning... didn't know it at the time though) and punched it, the truck stayed in first a lot longer than it normally would, which is obviously bc it had a trailer, but it does make me wonder about passing. I guess we will find out in roughly a month though.

tmo · June 15, 2016

Okay everyone, I'm back!! This time with better news that confused me. It's a long story!

Here goes: Today I picked up 1000 pounds of feed for the first time in my truck. That is 20 bags, each 50 pounds. The truck sat 2 inches lower in the rear with that weight and was completely level (one inch in the rear higher, but looked level as can be). So I had just left the feed store and was on a street before I got to the freeway and I figured I would reset my MGP's. The first number it read was 9 because I had just taken off from a red light, but when I got to cruising speed on the freeway at 75 it was reading 18. Then I turned off on a FM road (65-70 MPH) and it jumped up to 21-22. I was shocked. How the truck could get this good of mileage on the same roads that I drive everyday, but with a load of feed. I kind thought it was wrong but when I was close to home I checked the trip that I reset when I got fuel and it said 150 miles give or take on 3/4 of a tank. I usually am right above 100 at 3/4 of a tank and 200 at 1/2. I am so confused by this.

I have no idea what could have caused this. I am one guessing maybe the truck was much more level and was not a brick in the wind. Could have also been that there was less turbulence under the truck. But hey if I can get that kinda mileage again I might lower the rear and put stronger springs. Anyone else have similar stories. Maybe the opposite?

Nightwalker · June 15, 2016

I can't help you with mpg confusion,only way to really compare mpg is make same trip without the load around same time of day.i just wanted to tell you that I'm glad your happy with your v6.i didn't know they even made one for this this type of truck,till after I bought one.

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tmo · June 15, 2016

I can't help you with mpg confusion,only way to really compare mpg is make same trip without the load around same time of day.i just wanted to tell you that I'm glad your happy with your v6.i didn't know they even made one for this this type of truck,till after I bought one.

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I hope you are enjoying your truck! I actually did drive the truck directly after unloading. As soon as I got back on the highway for a few miles, the MPG screen had dropped back to 18.9 and lower as I continued to drive. It usually hovers around 17-17.5. I made a 30 mile round trip later yesterday afternoon and my MPG screen (without a reset) is on 17.8 (I haven't driven it since that time yesterday). Thanks for the reply!