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7.4 Or 8.1

toolman22ia

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toolman22ia Enthusiast

toolman22ia

Posted
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hey all im new here so take it easy on me. I have a 99 cc dually short box 4x4 7.4 107k miles near excellent condition. I pull a 12k pound 5th wheel almost every weekend but usually no more than 50 miles. The camper is about all the truck needs. I also am an avid bowhunter, but have another truck for that and everyday driving. gets around 15 mpg. That truck will be going to college in the fall with my son. Im thinking about selling the dually and getting something more suited for all my activitys. Ive been interested in an 02 2500hd 8.1 allison srw. its in very very good shape but has 125k miles and ext cab. Dont really need cc anymore kids gone. dont need drw for every day running. So any opinions for or against appreciated. nice to meet you all.

jro909 Senior Enthusiast

jro909

Posted
Posted

main issue with the 8.1 is the piss poor mileage and the oil consumption...besides that everything i've read its a stout drivetrain with the ally mated to it...the 6.0 is also a very stout motor

toolman22ia Enthusiast

toolman22ia

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main issue with the 8.1 is the piss poor mileage and the oil consumption...besides that everything i've read its a stout drivetrain with the ally mated to it...the 6.0 is also a very stout motor

 

 

im used to piss poor milage. the 7.4 only averages around 8-10.

cliobogger Enthusiast

cliobogger

Posted
Posted

yeah, 1qt to 1000 miles is concidered "normal"...i dont feel like checking/filling it that much. that was mainly in the 01/02s...gm supposidly fixed the issue in 03 on. so...yeah.

Ezrider_92356 Enthusiast

Ezrider_92356

Posted
Posted

not all 8.1;s have oil consumption problems but almost all big blocks period use some oil, theirs a lot of piston wall on a big block, and millage on a 8.1L 2500hd is gonna be better than your 7.4 drw. the oil consumption on my 8.1L i have not needed to add any oil between changes

yukon25008.1 Senior Enthusiast

yukon25008.1

Posted
Posted

ive had 3 8.1 trucks and theres no comparison to the 7.4 or the 6.0, if your pulling something/anything it does it effortlessly,

my 01 used some oil, this 04 doesnt at all. and after the blacbear tune my mileage is better.

chris23120 New Member

chris23120

Posted
Posted

My business uses 2 of these trucks for deliveries. We typically run 3-4k miles a week and are NOT adding oil weeky. The '05 uses about a quart every 4k and the '01 maybe a bit less. We run 11k avg on mobil one oil changes. Considering that they both have low oil lights that come on when its down a quart, and pressure gauges, on top of holding consderably more oil than a small block i really don't consider it a problem, especially since if i changed it at closer intervals i would be unaware.

As far as milage i would expect 24-40% better than your 7.4. Unloaded get that same as our 6.0 did, and better than it under load. The beauty of the 8.1 is in stock trim they run forever, and deliver 90% of their availiable torque from 1700-4300 rpm. This makes the truck drive like a much smaller vehical at part throttle. If you were towing more i would say get a duramax for the towing milage, but for your application i think you will be pleased with the 8.1.

arwriter Enthusiast

arwriter

Posted
Posted
What do you all think about 125k miles excellent condition. price 12k.

 

That seems like a fair price, that is assuming that the truck is not a base work truck model and it has tires with good serviceable tread.

jtramsey Enthusiast

jtramsey

Posted
Posted

I just traded a 2003 c2500hd 8.1 with the allison. with 132,00 it used 1 qt every oil change 3,000 miles. I think 12k is a liitle high unless it is a 4x4.

Ezrider_92356 Enthusiast

Ezrider_92356

Posted
Posted

i paid 13.5 for my truck in October with 90k miles on it 4wd alision 8.1 extended cab short box and it has alot of extra's such as the driver convenience plus package, factory tow package, deep tinted glass, off road skid plates, 3 way split bench seat, wideside body, and the upgrade package on the sterio, it has nice tasteful aftermarket rims, the bug deflector on the front and sides of the front windows. as well as aftermarket tint on the front two windows, also came with matinace records for the first 60k miles. dealer also put a new set of rubber on it there was a small crack in the windshield so he replaced the windshield and changed the engine and trans fluids for me.

 

i think i got a fair deal, i don't feel i over paid for the like new condition of the truck but i don't feel like i got a screaming deal ether.

 

at 12k with 125k miles assuming this is a dealership doesn't sound like a bad deal id see if you can get them to throw in some extra's on the deal and i think your be very happy.

toolman22ia Enthusiast

toolman22ia

Posted
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Well i went to a dealer today just to drive the 2002 2500hd with 8.1 and allison, and to see where we stood on trade. I went thinking that i wasn't even going to make a deal, and ended up coming home with it today. i got the price down $2500 and they are going to fix the paint flaws and small damage . I was shocked by the power difference between the 7.4 and 8.1. The 8.1 is the hardest running gasser out there. i have only had it for 4 hours and love it already. The only worries i have is the transmission. sometimes it downshifts hard coming to a stop. This could be just because i am not used to the allison. if not does anyone have any ideas? Thanks Also it has 4.10 gears also, would 285 tires help or hurt milage? Has anyone done this will they even fit? It has 265s on it know. Man it runs like a cut hound now.

yukon25008.1 Senior Enthusiast

yukon25008.1

Posted
Posted

the taller tire will help knock down the ratio a little, with the 8.1 and 4;10,s your not gonna see a difference going to the 285,s as far as mpg,s.. sure will look better though.

think it runs good now... wait until you do a decent intake and exhaust, and then let blackbear tune it.

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