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Which engine - 5.3, 6.2 or 3.0?

Z71RAD88
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Z71RAD88 Enthusiast

Z71RAD88

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I'm moving forward with a new truck purchase in the next few weeks and struggling to decide which engine to go with. I live in CA and don't tow. Typically drive 20,000 per year. My typical commute is 35 miles each way with 90% country roads at 55 mph and freeway at 65 mph, a combo of the two. I do get up the mountains frequently so the extra torque from the 6.2 and 3.0 appease me. I do understand having the turbo will be helpful at elevation compare to a NA engine. 

 

I was initially all set on the 6.2 but with the recent notice from NHTSA, It's got me thinking twice. 

 

Never owned a diesel and don't feel overly confident I can feed it the proper/required diesel living in California. 

 

What would you all go with? Trim level wise going RST or LTZ. Deals seem to be better on the LTZ with the 3.0. 

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newdude
newdude

Is it though?  I can reset my trip meter and drive 7 miles and get the same result.  That's not an accurate measurement of MPG, what it can achieve in a 7 mile stretch.        

Transient
Transient

I see that you ordered your truck before I was able to post my experience.  Imo, you made the right choice getting the 3.0 Duramax.  I have a 2020 with the 6.2 and lived in San Diego from 2020 to 2023

newdude
newdude

41mi.  Doesn't count.  Show us what you get on a tank or current lifetime MPG, that counts.  

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N715DP Enthusiast

N715DP

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I have a 3.0 and 16,000 miles later I am still amazed at the fuel efficiency over my 5.3 Avalanche I had previously.  I know gas prices are a different world on your side of the country but I ran a spreadsheet for almost 15,000 miles and came up with about 30% more cost efficient across all types of driving versus my Avalanche.  I see a roughly 50% increase in fuel economy so the 30% number takes into account the higher cost of diesel versus regular unleaded.  At typical highway speeds (I don't drive more than 70mph typically), I'm at more than 31mpg.  Around town is about 22mpg.  I know you mentioned not towing, but apples to apples towing, I was right on 50% more mpg with the same load over the same trip.

 

One thing I did not calculate is DEF usage but to be honest, it's so minimal of an expense that it's not worth factoring in.  

 

I think you'd find the fuel economy for your typical commute would be fantastic in the 3.0... I have the older 3.0 in my refreshed '22 and I've only heard that the newer is better in every way (including more power).

 

As for trim, I'm very happy with my Z71 RST, just enough bells and whistles without being a sticker shock situation.

Z71RAD88 Enthusiast

Z71RAD88

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Just now, N715DP said:

I have a 3.0 and 16,000 miles later I am still amazed at the fuel efficiency over my 5.3 Avalanche I had previously.  I know gas prices are a different world on your side of the country but I ran a spreadsheet for almost 15,000 miles and came up with about 30% more cost efficient across all types of driving versus my Avalanche.  I see a roughly 50% increase in fuel economy so the 30% number takes into account the higher cost of diesel versus regular unleaded.  At typical highway speeds (I don't drive more than 70mph typically), I'm at more than 31mpg.  Around town is about 22mpg.  I know you mentioned not towing, but apples to apples towing, I was right on 50% more mpg with the same load over the same trip.

 

One thing I did not calculate is DEF usage but to be honest, it's so minimal of an expense that it's not worth factoring in.  

 

I think you'd find the fuel economy for your typical commute would be fantastic in the 3.0... I have the older 3.0 in my refreshed '22 and I've only heard that the newer is better in every way (including more power).

 

As for trim, I'm very happy with my Z71 RST, just enough bells and whistles without being a sticker shock situation.

 

Thank you for your post! What kind of diesel do you have in PA? 

Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted

The 5.3 now and the 5.3 in your older Avalanche is not a good comparison in mpg. My 5.3 on a 650 mile trip got 25-27 mpg and around town it gets about 18- 20 mpg and iam not that easy on the peddle, yes the diesel will get a little better but you have to figure in the up charge for the diesel.

 

N715DP Enthusiast

N715DP

Posted
Posted

Standard ultra-low sulfur diesel is everywhere here (I think this is the same you'd have in CA).  In the winter, most stations switch to a winterized blend of #1 and #2 but I haven't noticed any difference in fuel economy or how the engine runs.  I typically fill up at one of the truck stops a few miles away as their prices are consistently less than your run-of-the-mill convenience store.  

 

 

Z71RAD88 Enthusiast

Z71RAD88

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Just now, Silverado4x4 said:

The 5.3 now and the 5.3 in your older Avalanche is not a good comparison in mpg. My 5.3 on a 650 mile trip got 25-27 mpg and around town it gets about 18- 20 mpg and iam not that easy on the peddle, yes the diesel will get a little better but you have to figure in the up charge for the diesel.

 

 

What year Silverado do you have in your 5.3 and trim level? And I would agree, the 5.3 with the 10 speed is a night and day difference compare to the 2004 and 2012 I had. 

Z71RAD88 Enthusiast

Z71RAD88

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Just now, N715DP said:

Standard ultra-low sulfur diesel is everywhere here (I think this is the same you'd have in CA).  In the winter, most stations switch to a winterized blend of #1 and #2 but I haven't noticed any difference in fuel economy or how the engine runs.  I typically fill up at one of the truck stops a few miles away as their prices are consistently less than your run-of-the-mill convenience store.  

 

 

 

We have very few #2 diesel stations left in the state from my research. It's all bio or renewable diesel. The owners manual states you can run up to B20 but it's recommended to use a condition or fuel additive with it. 

Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted

My other 5.3 was a 2019 with the 8 speed and I replaced it with a 2025 5.3 with the 10 speed, the 2025 hasn't been on that trip yet so iam expecting a little more but honestly I don't worry about mpg.

N715DP Enthusiast

N715DP

Posted
Posted
39 minutes ago, Z71RAD88 said:

 

We have very few #2 diesel stations left in the state from my research. It's all bio or renewable diesel. The owners manual states you can run up to B20 but it's recommended to use a condition or fuel additive with it. 

Hooray for the People's Republic of California! 🤣

Z71RAD88 Enthusiast

Z71RAD88

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Just now, PunchT37 said:

My ‘25 LT 2wd 5.3 with 3.42 gears has done this, at least at times. 
 

 

E36D1F76-2641-419B-94D2-A9312AF38EE2.jpeg

 

Wow. Impressive. Thanks for sharing. 

redwngr Senior Enthusiast

redwngr

Posted
Posted

My '23 3.0L has done this -- for 28,000 miles. 

This is all fuel used. 

Hand calc numbers are a little better than the DIC numbers. 

Lifetime average is at 29.2 usmpg.

 

image.png.9ccd2c72c11b3124374136aeb977b378.png

Z71RAD88 Enthusiast

Z71RAD88

Posted
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Posted
Just now, redwngr said:

My '23 3.0L has done this -- for 28,000 miles. 

This is all fuel used. 

Hand calc numbers are a little better than the DIC numbers. 

Lifetime average is at 29.2 usmpg.

 

image.png.9ccd2c72c11b3124374136aeb977b378.png

 

The 3.0 fuel mileage is absolutely unreal. Glad GM still has this as an offering in the half ton market. 

Z45 Senior Enthusiast

Z45

Posted
Posted

My last 3 trucks, '12, 17 and 21 were all 6.2l.  My 2024 I got the 3.0L diesel for the fuel economy.  I have 2 friend who bought earlier versions, 2020 and a 2021, both GMC's and they tell me no complaints. Granted this owners have kept their trucks stock, no suspension lifts or big tires. Like me they have them for basic transportation.

 

 

2024 GMC Sierra Denali Window Stikcer.pdf

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