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2005 Chevrolet Silverado C/2500 6.6 L V8

Camper_2012
Explorer
Explorer
I would like to buy 2005 Chevrolet Silverado C/2500 6.6 L6.6 L V8 diesel truck. Do you guys know what would be MPG for this truck. I own 26' 5th wheel (DW 7,900 GW 9,900). Thank You.
22 REPLIES 22

ksss
Explorer
Explorer
I am averaging about 9mpg with a combined weight of around 26K, pulling Fuzion in sig and Sea Doo in tow behind that. This is with my 06 LBZ, but I think it is still related to what you could expect at this weight.
2020 Chevy 3500 CC 4X4 DRW D/A
2013 Fuzion 342
2011 RZR Desert Tan
2012 Sea Doo GTX 155
2018 Chevy 3500HD CC LB SRW 4X4 D/A
2015 Chevy Camaro ZL1

LowRyter
Explorer
Explorer
what he said.

I get 11-12 towing at 60- 65 mph. 65 is a sweet spot for those 5 speed LLY trucks. Most trailer tires aren't beyond 65. Mine has never overheated but the fix is relatively simple and cheap.
John L
WW SL 2805 5th Wheel
2004.5 Chevy 2500HD Allison Duramax X Cab
Ducati 939 SS, Moto Guzzi V11 Sport, Moto Guzzi EV California and Suzuki 1200 Bandit

lazydays
Explorer
Explorer
I average between 10-12 mpg pulling my 12.6k lb. 5th wheel. It's never overheated and usually stays around 190 degrees during normal driving conditions. I have seen it hit 220 pulling a long grade once. The best thing I ever did was install EFI live with the heavy tow tune and turbo brake. The few extra hp made a big difference.
Very Patient Wife
Two Boys & a Girl
2013 Keystone Avalanche 345TG
2016 Chevrolet Silverado 3500HD 6.6L

kaydeejay
Explorer
Explorer
To the OP
I get 12-13mpg with truck in sig (similar to what you are looking at) pulling a fiver that weighs about the same as yours.
Note it is a 2005 LLY. It DID get warm enough for secondary fan to kick in a few times until I had the "GM fix" applied (LBZ aircleaner, which draws cool air from under the fender vs hot air from behind the rad).
Have not heard the secondary fan since.
So don't let the LLY haters scare you off!
Note, my truck is 2WD, which may help 1/2mpg or so.
Keith J.
Sold the fiver and looking for a DP, but not in any hurry right now.

NC_Hauler
Explorer
Explorer
Turtle n Peeps wrote:
FYI: The 06 LLY never had cooling issues. The 06 LLY was just a detuned LBZ so it had the same mouth piece and radiator as the LBZ.


Thx..couldn't remember...I went from an 05 LLY to the 07.5..sorry about that.
Jim & Kathy, (Boxers, Buddy & Sheba)
2016 Ram 3500 DRW Longhorn 4X4/CC/LB/Aisin/4.10/rear air assist ...Pearl White.
2016 DRV MS 36RSSB3/ W&D/ slide toppers/ DTV satellite/ 5.5K Onan propane gen.
B&W RVK3600 Hitch
Fulltiming in WV & TX
USAF 71-75 Viet Nam Vet

Camper_2012
Explorer
Explorer
Turtle n Peeps wrote:
Camper 2012 wrote:
Turtle n Peeps wrote:
Year after year I get 12 towing my 28' TT at 70 to 75 MPH with my LBZ. This is over 10's of thousands of miles across the western/ mid western US towing.

I know it would pull down 13+ MPG if I slowed down to 55 or 60 MPH but I don't have that much time on vacation so I tow fast and take the penalty.

Keep in mind that my trailer is old so it's heavy for it's size. I'm around 16K combined gross.

On the highway solo I can get 19/20 and mixed I get 16 and change.
Is your truck 6.6L?


Yes, all Dmax, 2001-2014 2500 & 3500 series pickups are 6.6 liter diesels. All have a 3.73 rear end. 2001-2005 had 5 speed automatics (unless they were a stick) 2006 on up have 6 speed automatics (unless they were sticks).

It's to note that a "few" LLY engines (the engine your looking at) had heating problems. These problems can be fixed with a new turbo mouth piece and/ or a new LBZ radiator.

It's also to note that this engine will get slightly less, (1/4 to 1/2 MPG) and I do mean slightly less fuel mileage than the LBZ engine.

Also my truck is a 4X2 with street tires for maximum mileage. Like I said, these figures are "average" over many years of driving it.
Thank you.

Camper_2012
Explorer
Explorer
rjstractor wrote:
Camper 2012 wrote:
Is your truck 6.6L?


All Duramax diesel engines in Chevy or GMC pickups are 6.6 liters. There are many variations but all are the same displacement.

Thank you so much.

Camper_2012
Explorer
Explorer
macsplinter wrote:
I have a 2005 duramax and pulling a 6500# 29' TT I get from 9 to 12 mpg depending on hills.
Thank You so much for your post. Have a nice day.

Turtle_n_Peeps
Explorer
Explorer
FYI: The 06 LLY never had cooling issues. The 06 LLY was just a detuned LBZ so it had the same mouth piece and radiator as the LBZ.
~ Too many freaks & not enough circuses ~


"Life is not tried ~ it is merely survived ~ if you're standing
outside the fire"

"The best way to get a bad law repealed is to enforce it strictly."- Abraham Lincoln

NC_Hauler
Explorer
Explorer
Turtle n Peeps wrote:
Camper 2012 wrote:
Turtle n Peeps wrote:
Year after year I get 12 towing my 28' TT at 70 to 75 MPH with my LBZ. This is over 10's of thousands of miles across the western/ mid western US towing.

I know it would pull down 13+ MPG if I slowed down to 55 or 60 MPH but I don't have that much time on vacation so I tow fast and take the penalty.

Keep in mind that my trailer is old so it's heavy for it's size. I'm around 16K combined gross.

On the highway solo I can get 19/20 and mixed I get 16 and change.
Is your truck 6.6L?


Yes, all Dmax, 2001-2014 2500 & 3500 series pickups are 6.6 liter diesels. All have a 3.73 rear end. 2001-2005 had 5 speed automatics (unless they were a stick) 2006 on up have 6 speed automatics (unless they were sticks).

It's to note that a "few" LLY engines (the engine your looking at) had heating problems. These problems can be fixed with a new turbo mouth piece and/ or a new LBZ radiator.

It's also to note that this engine will get slightly less, (1/4 to 1/2 MPG) and I do mean slightly less fuel mileage than the LBZ engine.

Also my truck is a 4X2 with street tires for maximum mileage. Like I said, these figures are "average" over many years of driving it.


Thanks, that is what I was trying to tell him on his other thread as well as this one, but evidently he didn't read them......

Wasn't going to go with LBZ, LML, LLY ect because OP didn't seem to know that the 6.6 WAS /IS the D/A engine. and the 05'-06' LLY did have cooling issues, though I think the 05' was more troublesome than the 06? I had the 05', and only once did I "heat up", but nothing else happened.

I owned quite a few Chevy D/A combo's..that was what I was telling you..I would go to web site: thedieselplace...it's all about Chevy/GM duarmax allisons and each forum covers certain year diesels...You may be able to learn a little more about them and what you want to purchase....The Allison transmission has a grade braking feature that is great.

Dodge??? Where did I say anything about buying a Dodge, you were asking about Chevy 6.6L diesels and I've owned and towed with them and was giving you information on them.
Jim & Kathy, (Boxers, Buddy & Sheba)
2016 Ram 3500 DRW Longhorn 4X4/CC/LB/Aisin/4.10/rear air assist ...Pearl White.
2016 DRV MS 36RSSB3/ W&D/ slide toppers/ DTV satellite/ 5.5K Onan propane gen.
B&W RVK3600 Hitch
Fulltiming in WV & TX
USAF 71-75 Viet Nam Vet

NC_Hauler
Explorer
Explorer
Camper 2012 wrote:
NC Hauler wrote:
Camper 2012 wrote:
I would like to buy 2005 Chevrolet Silverado C/2500 6.6 L6.6 L V8 diesel truck. Do you guys know what would be MPG for this truck. I own 26' 5th wheel (DW 7,900 GW 9,900). Thank You.


So the other thread you started that is 9 pages long wasn't helpful enough that you start another one?

If you use the D/A abbreviation, most will know it's a Duramax/Allison set up and most will know that is the 6.6L ....If the GVW of the 5er is only 9900#, you should get pretty decent mileage, I don't know how fast you tow, or how heavy you will laden your truck, but the truck won't have any issues at all towing a 5er that weighs under 10,000#..I would think towing, maybe 12 mpg? Just a guess on my part though
I did not like dodge other trucks.Thanks.


:h huh?? Didn't say anything about Dodge trucks?????, I have no clue what you just posted. I was answering your question about a Chevy 6.6L 8 cylinder diesel engine. I just stated you started another thread and left the other one hanging that you started.

I also was trying to be helpful...Understand that when you ask about a diesel engine in the Chevy or GM...At this time, there is only ONE, from 2001 till 2015 built Chevy/GM diesel engines ... They are ALL the 6.6L 8 cylinder that you keep asking others if that's what they have...If they say, LBZ, LML, whatever, if they state they have the diesel , which is what you're asking about....it ONLY comes in a 6.6L 8cylinder diesel engine. Was trying to tell you that and answered your towing question....
Jim & Kathy, (Boxers, Buddy & Sheba)
2016 Ram 3500 DRW Longhorn 4X4/CC/LB/Aisin/4.10/rear air assist ...Pearl White.
2016 DRV MS 36RSSB3/ W&D/ slide toppers/ DTV satellite/ 5.5K Onan propane gen.
B&W RVK3600 Hitch
Fulltiming in WV & TX
USAF 71-75 Viet Nam Vet

Turtle_n_Peeps
Explorer
Explorer
Camper 2012 wrote:
Turtle n Peeps wrote:
Year after year I get 12 towing my 28' TT at 70 to 75 MPH with my LBZ. This is over 10's of thousands of miles across the western/ mid western US towing.

I know it would pull down 13+ MPG if I slowed down to 55 or 60 MPH but I don't have that much time on vacation so I tow fast and take the penalty.

Keep in mind that my trailer is old so it's heavy for it's size. I'm around 16K combined gross.

On the highway solo I can get 19/20 and mixed I get 16 and change.
Is your truck 6.6L?


Yes, all Dmax, 2001-2014 2500 & 3500 series pickups are 6.6 liter diesels. All have a 3.73 rear end. 2001-2005 had 5 speed automatics (unless they were a stick) 2006 on up have 6 speed automatics (unless they were sticks).

It's to note that a "few" LLY engines (the engine your looking at) had heating problems. These problems can be fixed with a new turbo mouth piece and/ or a new LBZ radiator.

It's also to note that this engine will get slightly less, (1/4 to 1/2 MPG) and I do mean slightly less fuel mileage than the LBZ engine.

Also my truck is a 4X2 with street tires for maximum mileage. Like I said, these figures are "average" over many years of driving it.
~ Too many freaks & not enough circuses ~


"Life is not tried ~ it is merely survived ~ if you're standing
outside the fire"

"The best way to get a bad law repealed is to enforce it strictly."- Abraham Lincoln

rjstractor
Nomad
Nomad
Camper 2012 wrote:
Is your truck 6.6L?


All Duramax diesel engines in Chevy or GMC pickups are 6.6 liters. There are many variations but all are the same displacement.
2017 VW Golf Alltrack
2000 Ford F250 7.3

Camper_2012
Explorer
Explorer
NC Hauler wrote:
Camper 2012 wrote:
I would like to buy 2005 Chevrolet Silverado C/2500 6.6 L6.6 L V8 diesel truck. Do you guys know what would be MPG for this truck. I own 26' 5th wheel (DW 7,900 GW 9,900). Thank You.


So the other thread you started that is 9 pages long wasn't helpful enough that you start another one?

If you use the D/A abbreviation, most will know it's a Duramax/Allison set up and most will know that is the 6.6L ....If the GVW of the 5er is only 9900#, you should get pretty decent mileage, I don't know how fast you tow, or how heavy you will laden your truck, but the truck won't have any issues at all towing a 5er that weighs under 10,000#..I would think towing, maybe 12 mpg? Just a guess on my part though
I did not like dodge other trucks.Thanks.