5.3L vs. 6.0L Questions

[Idaho Outlaw]

I've been shopping for a new(er) pickup, and keep coming accross either the 5.3L in the 1/2 ton and/or 6.0L in the 3/4 ton pickups.

My dad and brother have had 5.7L in their's (97/98) with 15'ish MPG and lots of power. My dad also had an 03' with the 6.0, and said it was a steaming pile with poor gas mileage, and later traded it in on a Duramax. I know nothing about the 5.3L. Can anyone please give me some insight.

[Idaho Outlaw]

Another question.

I've been doing some searching/reading, and have found that the 6.0L gets either around 10MPG or 13.5MPG. For those of you who have this motor, what gear's do you have associated to the MPG you are getting? 3.73/13MPG? 4.10/10MPG?

[pcmcobra]

I just bought an 07 gmc w/ the 5.3
Sticker claims 16/city 22/hwy w/ 3.42 gears.
It's just about spot on.

[62 short step]

I have an 07 classic with the 6.0. It gets 11 to 13 mpg in the city pulling a 7x14 enclosed trailer every day. On the highway pullin nothing it will get 17 at best doing about 70 to 75 mph. It has 4.10 gears and is a 4x4 2500 hd. My uncle has a 2000 chevy z71 with the 5.3 he gets about 17 to 19 hwy and 12 to 15 around town. But I prefer the 6.0 to haul with, has the extra grunt to pull.

[N2TRUX]

I have had a couple of each so lets see what I can come up with.


06 Silverado 5.3 3.42 average 15 city- 20 hwy
05 Silverade 5.3 3.73 average 14 city- 19 hwy
03 Denali XL 6.0 3.42 average 13 city- 17 hwy
02 1500HD 6.0 3.73- average 15 city-17 hwy


If you don't need an HD truck, your best bang for the buck is a 5.3 with 3.73 gears. My 05 Silverado extra cab with 3.73's will run circles around my 06 Silverado Crewcab with 3.42 gears.

If I drive it with fuel mileage in mind the 06 gets 2-3 mpg better, but thre is a huge trade off in low end power.

[Idaho Outlaw]

Thanks for the great feedback. I have come to the conclusion, that no matter which set-up I purchase, I am going to be pretty happy.

The pickup I am looking at is a 02' 2500hd 6.0L 5-spd Manual. The only issue's I have seen through my searching the forum is 'piston slap', and I think that is just luck of the draw. I just need to listen for it while test driving.

[glock35ipsc]

Originally Posted by N2TRUX

02 1500HD 6.0 3.73- average 15 city-17 hwy

I have the same truck (GMC), and thats right where I'm at. I also have a Wait4Me Performance tuned PCM, and it made a HUGE difference pulling my 5th wheel and the enclosed snowmobile trailer. I get 10-13 pulling, depending on which trailer I am pulling, which usually dictates the terrain I'm in. The snowmobile trailer means I'm always going uphill.

[Gray Ghost]

Originally Posted by N2TRUX

03 Denali XL 6.0 3.42 average 13 city- 17 hwy

Is this a GMC Sierra Denali? That's good mileage for an AWD 6.0. IS this the EPA numbers or yours?

[1LoC10]

Originally Posted by Gray Ghost

Is this a GMC Sierra Denali? That's good mileage for an AWD 6.0. IS this the EPA numbers or yours?

No, the XL means its a Suburban style SUV

[Z-71]

My 07 Vortec Max/6.0 1500 gets around 14 city and 16 Interstate. But, if you cruise state highways at about 61 mph it will get close to 21. Active fuel management definitely works.

[Strodder]

I heard the earlier 6.0's didn't have that Active Fuel Management like the 5.3 had. I have a 06 2500HD Crew Cab and get 10mph around town with 3:73 gears, and 10 to 11 towing my 26' Toy Hauler pull trailer. I added a Volant Cold air system, a Hypertech, and has a Magnaflow exhaust. Didn't make that much difference in mileage. Power is OK, but my 03 Extra Cab 5.3 with the same stuff done to it would kick it's a**. But not towing.

[chuckmc8]

my 00 Z71 with 5.3 and 3:73 averages about 15.5 or so. it has a K&N filter and flomaster, otherwise stock. I plan to disconnect the hot water connection to the throttle body and see if that helps a little also.
i would like a "smooth"air intake tube and performance tune-

[Z-71]

Originally Posted by Strodder

I heard the earlier 6.0's didn't have that Active Fuel Management like the 5.3 had. I have a 06 2500HD Crew Cab and get 10mph around town with 3:73 gears, and 10 to 11 towing my 26' Toy Hauler pull trailer. I added a Volant Cold air system, a Hypertech, and has a Magnaflow exhaust. Didn't make that much difference in mileage. Power is OK, but my 03 Extra Cab 5.3 with the same stuff done to it would kick it's a**. But not towing.

The L76(aluminum block) engine did have it, the LY6(cast iron block) engine did not.

[Strodder]

Originally Posted by Z-71

The L76(aluminum block) engine did have it, the LY6(cast iron block) engine did not.

That's a shame. I wonder why.

[Z-71]

Originally Posted by Strodder

That's a shame. I wonder why.

Really don't know, the LY6 was mainly used in HD trucks so maybe that plays into it.

[gmcracing92]

i have an 05 sierra denali crew cab. 6.0 awd 3.73 it gets around 12-14 city adn 15-18 highway depends how hard i drive it i have a aem cold air intake, true dual exhaust 2.5 magnanflow mufflers in to 4x18" magnaflow tips. i love my 6.0, i wouldnt trade it for anything but a 6.2

[Z-71]

Originally Posted by gmcracing92

i have an 05 sierra denali crew cab. 6.0 awd 3.73 it gets around 12-14 city adn 15-18 highway depends how hard i drive it i have a aem cold air intake, true dual exhaust 2.5 magnanflow mufflers in to 4x18" magnaflow tips. i love my 6.0, i wouldnt trade it for anything but a 6.2

Yeah, i would like a 6.2 but the 6.0 is still way better than the 5.3.

[Mister laugh]

Originally Posted by Idaho Outlaw

Thanks for the great feedback. I have come to the conclusion, that no matter which set-up I purchase, I am going to be pretty happy.

The pickup I am looking at is a 02' 2500hd 6.0L 5-spd Manual. The only issue's I have seen through my searching the forum is 'piston slap', and I think that is just luck of the draw. I just need to listen for it while test driving.

Look at that truck really hard, from what I understand the 6.0l's never came as a manual from the factory I wanted one.

[Blitz]

Ok to add to that...I'll be "that" guy...what about from a sporty standpoint? Say if you rarely tow anything BUT you want something performance minded VS. those days when you're low on cash and are MPG minded. lol

So essentially...Performance (late and in a hurry) vs. MPG (Country crusing)?

5.3 or jump straight to 6.2?

[Gray Ghost]

Originally Posted by Mister laugh

Look at that truck really hard, from what I understand the 6.0l's never came as a manual from the factory I wanted one.

Actually they did come with manuals [althought they are rare]. My construction foreman has one. His is a regular cab longbed 2500HD with a 5 sp manual.

A wierd thing happened yesterday on the way home with my new ride...I saw a 1500HD....didn't know that was available, but there it sat at a lite. Wish I had my camera at the time...had to do a double take.

[Mountaineer 1977]

If you want the tow abilities of the 6.0, look at the 1/2 with the Vortec Max package. It gets a 6.0 but it is different the 6.0 in the HDs. I have a 07 1500HD, gets about 13 to 14 on the highway with 4.10. I had a 04 1/2 4x4 5.3 and it got 17 to 18 on the highway. I have 30 ft camper, so the 6.0 helps.

[Z-71]

Originally Posted by Blitz

Ok to add to that...I'll be "that" guy...what about from a sporty standpoint? Say if you rarely tow anything BUT you want something performance minded VS. those days when you're low on cash and are MPG minded. lol

So essentially...Performance (late and in a hurry) vs. MPG (Country crusing)?

5.3 or jump straight to 6.2?

Once you go to a 6.0 or a 6.2, there is no going back to a 5.3. The Vortec Max 6.0 seems to feel more for performance than the 6.0 in the HD. A lot of that has to do with the tranny and the rearend. But, the Vortec Max's seem to be more "free spirited" so to speak than any HD that i have driven, including the 1500 HD. Now the 6.2 is definitely for sport.

[Mister laugh]

Originally Posted by Gray Ghost

Actually they did come with manuals [althought they are rare]. My construction foreman has one. His is a regular cab longbed 2500HD with a 5 sp manual.

A wierd thing happened yesterday on the way home with my new ride...I saw a 1500HD....didn't know that was available, but there it sat at a lite. Wish I had my camera at the time...had to do a double take.

I am not saying i don't believe you, but is there any way you could get a picture of the RPO's on that truck? I have had this debate with some other people and no one could come up with the RPO for a 5.3 or 6.0 manual, if it was possible i would drive across the country to buy a 5spd 6.0l

[glock35ipsc]

Originally Posted by Gray Ghost

A wierd thing happened yesterday on the way home with my new ride...I saw a 1500HD....didn't know that was available, but there it sat at a lite. Wish I had my camera at the time...had to do a double take.

I had a 2002 GMC 1500HD, it was an awesome truck! I pulled a fifth wheel RV and a snowmobile trailer thousands of miles without ever a hiccup.

[Gray Ghost]

Yep, sure can...I should see him today unless it rains all day.