5.3l For Towing? Gmt 700 Vs Gmt 900 With And W/o Afm?

Jettix2 · August 19, 2008

Hey guys;

Just doing some research here...........it's a buyers market for full-size trucks right now, and I've got an '06 Tundra I'm itching to turn-in on the lease.

Was considering getting a new GMT900 '09 Silverado LTZ 4WD with the 6.2/6 Speed..............

But, here's the scenario:

My wife and I already have 2 very nice cars. The truck is to be used for:

1) Light business use (hauling retail items from our store to the post office, occasionally).

2) Plowing my short driveway in the winter (SnowBear lightweight plow)

3) Hauling our Camper on 4-6 camping trips each summer (each trip < 500 miles). Total trailer weight currently is 4600#, if we got a new camper it would have sliders and would be in the 6500# range (25-28 foot range).

Total annual mileage will only be 8,000, if I'm lucky. Seems really stupid to spend $35,000 on a new Silverado to not drive it very often.

I think it would be smarter to snag a very nice GMT 700 '04-06 Sierra Crew Cab 4WD with the 5.3L for $15-17K, something with low miles (30-40k) and still have a NICE truck that won't depreciate as much, etc etc.

1) SO.........how bad is the fuel economy with the older 5.3? I read the MPG poll, and it sucks, compared to the 19.XX that my parents get with their '08 Escalade 6.2L )))..............I know the older GMT700 5.3L didn't have AFM or any of that stuff...........does it really help on MPG very much?

2) Is the 5.3L going to tow noticably better than my '06 Tundra (last year of the 1st gen, 4.7L has 271hp @ 5400 and 313 ft/lb at 3400 w/ a 5 speed automatic)??? I hope so, because the Tundra is really flat-footed towing this trailer, IMHO. I'd buy the 6.0L, but I know they REALLY suck fuel:)

3) I'd certainly entertain running a programmer to get better MPG/HP out of the 5.3L

4) Which rear-end should I try to get? Does the Z-71 automatically come with the 3.73??

Any thoughts are appreciated............

Thanks, Ben

tnord · August 19, 2008

i used to haul 4500-5000lb on my 18' car hauler with an 01 Z71 Silverado w/5.3. it did alright in the power department, not great, but got the job done without too much fuss. doing 72-75mph i got between 10 and 11.5mpg depending on the wind.

Z71's all have the 3.73 i think.

if you went to a 24' 6500lb camper, i'd for SURE get the 6.0 or better. if i put any more weight or wind resistance on my rig, it'd struggle. my new 08 i expect to fair much better though, as it has about 131k fewer miles.

Vortec-Z71 · August 19, 2008

Hey guys;

Just doing some research here...........it's a buyers market for full-size trucks right now, and I've got an '06 Tundra I'm itching to turn-in on the lease.

Was considering getting a new GMT900 '09 Silverado LTZ 4WD with the 6.2/6 Speed..............

But, here's the scenario:

My wife and I already have 2 very nice cars. The truck is to be used for:

1) Light business use (hauling retail items from our store to the post office, occasionally).

2) Plowing my short driveway in the winter (SnowBear lightweight plow)

3) Hauling our Camper on 4-6 camping trips each summer (each trip < 500 miles). Total trailer weight currently is 4600#, if we got a new camper it would have sliders and would be in the 6500# range (25-28 foot range).

Total annual mileage will only be 8,000, if I'm lucky. Seems really stupid to spend $35,000 on a new Silverado to not drive it very often.

I think it would be smarter to snag a very nice GMT 700 '04-06 Sierra Crew Cab 4WD with the 5.3L for $15-17K, something with low miles (30-40k) and still have a NICE truck that won't depreciate as much, etc etc.

1) SO.........how bad is the fuel economy with the older 5.3? I read the MPG poll, and it sucks, compared to the 19.XX that my parents get with their '08 Escalade 6.2L )))..............I know the older GMT700 5.3L didn't have AFM or any of that stuff...........does it really help on MPG very much?

2) Is the 5.3L going to tow noticably better than my '06 Tundra (last year of the 1st gen, 4.7L has 271hp @ 5400 and 313 ft/lb at 3400 w/ a 5 speed automatic)??? I hope so, because the Tundra is really flat-footed towing this trailer, IMHO. I'd buy the 6.0L, but I know they REALLY suck fuel:)

3) I'd certainly entertain running a programmer to get better MPG/HP out of the 5.3L

4) Which rear-end should I try to get? Does the Z-71 automatically come with the 3.73??

Any thoughts are appreciated............

Thanks, Ben

1999-2007 Classic Silverados and Sierras were on the GMT800 platform. The only downside to the 1500 Crew cab is the 5 1/2 foot bed. I would recommend the 1500HD which comes with the 6 1/2 foot bed, but it comes with the 6.0L engine. I don't do much towing or plowing, but I'm sure someone else can chime in about that. Also, make sure you get the 3.73 or 4.10 gears, preferably the 4.10 for towing heavy loads. As for MPG, I can usually squeeze out around 17-18. But that is mostly highway driving.

Jettix2 · August 19, 2008

Oops, sorry, GMT 800 and 900 )

1) 5.5 ft bed is OK for my needs.

2) Current trailer is a Coachmen Catalina Lite 25 FT and weighs 4600#

How much difference in mileage between the old 5.3 and old 6.0? ("old" being pre-AFM) A guy I know has an '02 or '03 Silverado 2500 2WD with the 6.0 and gets 11-12mpg with it......OUCH!

(To clarify, if the road is flat and there is no wind, my Tundra will pull the 4600# trailer OK. If there's even a 15mph headwind, the truck is sweating bullets trying to maintain 55-60mph.)

Thanks,. Ben

tnord · August 19, 2008

all reports from my friends that haul around enclosed race trailers say you're pretty much stuck with 9-10mpg towing, no matter what truck you have.

i would expect 14mpg combined use with a 6.0, and 15mpg with the 5.3. i don't think the AFM helps much, maybe 1/2 to 1mpg improvement. unless you're coasting, it doesn't really come on.

Nick The Great · August 19, 2008

I might get flamed for this, but you sound like a good candidate for a diesel truck.

I mean it sounds like you're 85% towing with a little blading. I don't have much experience using a truck for a snowplow (I use a shovel ) so maybe that's not a good idea. Also, I don't know what a used diesel truck goes for, but it could pencil out.

C & A s Dad · August 19, 2008

If you will be upgrading to a 6500 lb camper I would strongy suggest the 4.10 gears no matter which year model you buy. I tow a 6500 29 ft camper with my Yuk XL and it does very well but it does have 4.10 gears. The 5.3 has a sweet spot around around 2400 rpms or so and with 4.10s pulling in 3rd, you will be right in that sweet spot most of the time. If you keep the camper you have, 3.73s would do the job pretty well.

csheatz · August 19, 2008

i have a 06, 5.3 (L33) it is a Z71, and it has a 3.43 rearend. I tow a 19' trailer, close in weight to yours, its fine. i get 11.5 when towing and 18-19 rest of the time. the only thing i would suggest is that you get the 3.73, or 4.10. I dont have a issue with mine and have pulled loads close to 6500lbs, with no issues. i would buy the truck all over again. however next truck will be the VMAX, juse because thats what i want. not sure i need.

bbwb · August 19, 2008

I have an '06 Sierra with the all aluminum 5.3, Z71 and tow package, that originally came with the 3.42 ratio...I had to upgrade to the 4.10's to pull my camper. I struggled with the 3.42's on hills and slight headwind while pulling my camper (loaded tractor/trailer rigs were passing me on the hills). It not so much a problem pulling on the flats but the hills are a killer (also the wind drag from the camper). With the 4.10's I get around 9 mpg at 60/65 mph, 18 mpg without.

bbwb