bmanning wrote: Nice truck! The 11'-up strengthened GM/Chev chassis is very impressive.
Update us on your MPG #s after a few tanks of use if you don't mind; I am curious as to what the 6.0L with the 6sp behind and 4.10s gets in daily/mixed driving.
I have a 2011 crew 3:73 I get 13 mpg 11 mpg towing
I have the same setup in my dually. 13 mpg is the best I've got empty. With my TT (7,000 lbs) I don't even use the tow haul mode. The book says you don't need to unless your over 75% of your gross. I would tow mostly in M5 and got about 8 mpg.
I'm off to pick up a 13,500 GVW 5er this weekend so my towing world is up for an adjument period.
2012 Chevy 3500HD Dually 4X4
Crew Cab long bed 6.0 gasser 4.10
06 Hitchiker II LS 29.5 FKTS
Yamaha EF3000iSE
retired gadgetman
I had a 2008 2500 4x4 with the 6.0 gas engine. It had plenty of power but it liked gas a little too much for me. Also I found that when the trans would down shift from sixth to fifth it stayed there way too long. I live in Florida and we all know how big our hills are down here. LOL One day I was heading down towards Tampa empty with the cruise set right at 70 MPH, it would down shift to fifth and stay there. I would be up and down the next grade, a mile or so, and it would not move back into sixth. I had the dealer do the re-learn and tried it again but it was always the same thing. I would have to cancel the cruise and let the gas fall of until it hit sixth then put the cruise back on.
I towed my old TT which was right around 11,000 pounds to Daytona in July for the NASCAR race. Door to door is 140 miles. I stopped for gas as I was not sure I would have made the trip on one tank.
All of this aside the truck had all kinds of power but I decided to trade it in on my 2005 DuraMax and I have never regretted my decision.
I am a Retired U.S. Merchant Marine Chief Engineer
05 Chevy 2500 4x4 D/A with Helper Springs and Air Ride Air Bags
06 R-Vision RW3360 Fifth Wheel Toy Hauler
97 FLTCI converted into a Roadsmith Trike by The Trike Shop of Daytona
If you put the trans into M the grade control mechanism of the transmission is turned off. Better to leave it in D and turn on the Tow/Haul mode. Using Tow/Haul mode minimizes the shifting up and down and keeps the trans running cooler and it will last longer. You can also disable the overdrive so that the transmission will not shift into 5th or 6th gear but overall better to let the truck do the work and use D and T/H enabled.
You paid for a very sophisticated tow vehicle. Shifting it into M essentially is shutting off all the smarts that you paid for when you bought the truck.
The manual is confusing as the information is all over the place but it is worth taking the time to review it all.
You can also monitor the transmission fluid temperature and verify which approach keeps it lower with a heavy load.
TugCE wrote: Also I found that when the trans would down shift from sixth to fifth it stayed there way too long. I live in Florida and we all know how big our hills are down here.
Your truck was telling you something. It should have never been in 6th gear in the first place! Weight is not the problem, power is. The 6.0L does not have sufficient torque at 1700rpm in 6th gear to overcome the aerodynamic drag. Keep it in 5th gear, 2100-2500rpm and be happy. All the games you play trying to achieve 6th gear probably cost you 1mpg over just keeping the lower gear the whole time. But you've moved on to the right power train if you expect to never exceed 2000rpm. while towing.
elkhornsun wrote: If you put the trans into M the grade control mechanism of the transmission is turned off. Better to leave it in D and turn on the Tow/Haul mode....You can also disable the overdrive so that the transmission will not shift into 5th or 6th gear
The experience of the previous poster is exactly why you use manual mode. Grade control is not as important and one can always manually grade control it. I am not aware of any way to lock out the two overdrive gears except using manual mode, which acts like a normal automatic transmission choosing to shift when it wants to but limits the top gear.
A & A parents of DD 2005, DS1 2007, DS2 2009 2011 Suburban 2500 6.0L 3.73 pulling 2011 Heartland North Trail 28BRS 2012 VW Passat TDI
2008 Duramax to 2011 6.0 tough decision. I know the 2011 has the beefed up frame but giving up a Duramax would be hard to do. Was 2008 during the period when diesel MPG really suffered?
I think I'd want the Duramax if pulling 11.8K.
07'Duramax dually,12'Open Range 399BHS
Hawkshead TPMS,Hensley BD3,Killerbee exhaust brake
Blue Ox Bedsaver,air bags w/compressor
Arvika pin box bike rack,Bak Flip tonneau cover
5500 Onan LP,EMS-HW-50
14'Porta Bote w/8.0 Nissan
Vu Cube 2000,Splendide 2000S
I have a 2011 Silverado 2500HD CCSB with the 6 liter, 3.73 rear end, Z85 pkg, and 18" wheels. I was getting 10-13 bumming around no trailer, 8-9 with our Jayco. Then I started putting in 91 octane with no ethanol and my mileage had increased significantly. I now get on average 15.5 to 17 MPG bumming around and can see 19 to 22 MPG if given a calm day or tailwind. Towing the Jayco I got 12-13 MPG. Truck currently has 11,700 miles on it and power seems to always be getting better. We are looking to upgrade to a 2013 Jayco Eagle 28.5 RLS 5th wheel so we'll see how it does then. Probably will wish we had the 4.10 rear end.
2011 Chevrolet Silverado 2500HD Crew Cab 4x4
2011 Jayco 26BH
TugCE wrote: Also I found that when the trans would down shift from sixth to fifth it stayed there way too long. I live in Florida and we all know how big our hills are down here.
Your truck was telling you something. It should have never been in 6th gear in the first place! Weight is not the problem, power is. The 6.0L does not have sufficient torque at 1700rpm in 6th gear to overcome the aerodynamic drag. Keep it in 5th gear, 2100-2500rpm and be happy. All the games you play trying to achieve 6th gear probably cost you 1mpg over just keeping the lower gear the whole time. But you've moved on to the right power train if you expect to never exceed 2000rpm. while towing.
elkhornsun wrote: If you put the trans into M the grade control mechanism of the transmission is turned off. Better to leave it in D and turn on the Tow/Haul mode....You can also disable the overdrive so that the transmission will not shift into 5th or 6th gear
The experience of the previous poster is exactly why you use manual mode. Grade control is not as important and one can always manually grade control it. I am not aware of any way to lock out the two overdrive gears except using manual mode, which acts like a normal automatic transmission choosing to shift when it wants to but limits the top gear.
This is for APT, please reread my post and answer a question for me if you would, please.
If I was in the wrong gear, please tell my what gear I should use in the following situation. Running down a mostly FLAT interstate highway in FLORIDA with NO TRAILER and a EMPTY BED??? Oh, I forgot to mention in my first post that I had my Roll N Lock bed cover closed.
Anyone that has towed know that you sometimes need to lockout a gear when loaded heavy.
270wsmhunter wrote: I have a 2011 Silverado 2500HD CCSB with the 6 liter, 3.73 rear end, Z85 pkg, and 18" wheels. I was getting 10-13 bumming around no trailer, 8-9 with our Jayco. Then I started putting in 91 octane with no ethanol and my mileage had increased significantly. I now get on average 15.5 to 17 MPG bumming around and can see 19 to 22 MPG if given a calm day or tailwind. Towing the Jayco I got 12-13 MPG. Truck currently has 11,700 miles on it and power seems to always be getting better. We are looking to upgrade to a 2013 Jayco Eagle 28.5 RLS 5th wheel so we'll see how it does then. Probably will wish we had the 4.10 rear end.
I WANT TO BELIEVE! I WANT TO!
I'm going to drain my tank, and find some ethanol free gas. If that works, I owe you a bottle of 12 year old scotch.
I misread the empty part, TugCE. I thought it was towing the TT. Was this experience using tow/haul mode or regular?
My truck can hold 6th gear without towing at 75mph up most hills. It downshifted a few times to 5th in the Appalachian mountains on I77 and I75 on my 2600 mile trip Mi->FL and back. You are right to think it should mostly hold 6th gear at a steady speed anywhere in FL except some overpass hills.
270wsmhunter,
Most people who use gasoline with no ethanol report similar improvements in fuel economy. If you can find some 87 octane without it, I would welcome your FE numbers for comparison. I wish I knew where to buy it in MI. All I see now are E10.
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