I just bought an 03 2500 5.9 automatic Quad 4X4 with 63000 miles. Truck is immaculate, one owner, untouched to my knowledge, the dude that had it before me kept detailed records of maintenance and from what I saw it was maintained and the suggested times and mileage. My last Dodge was an 08 Hemi, which I loved but had to part ways with it. I know about the mod bug and would like to stay away from it, at least for a while. The truck will, for now, tow my boat and is not a daily driver. There are a few questions that I have if you guys wouldnt mind chiming in.

1. Right now on the highway (no load) I average 19 can that get better and with what?

2. I am not interested, right now, in huge amounts of horsepower but down the line I am sure that will happen. From what I have read the stock trannys are @ss, so would it be better to have the stocker rebuilt or buy aftermarket?

3. Which up grades should I be looking to do to the truck because of the age and miles (stock parts that might be at the end of their life)?

4. Any other suggestions you guys may have.

 

Congrats we are ganna need pictures. But from what I was told a couple weeks ago when I was exactly in your spot was upgrading the stock tranny is just fine. The first thing I was told to do is get a fass or airdog lifter pump. If you plan on towing get gauges put in trans, fuel pressure, boost, EGT. I'm sure there stuff im forgeting but others will chime in.

 

The first thing I did when I had purchase my 04 was change the gears. Went with 4.10 gears BC I was hotshotting at the time. And I bought an edge performance chip for it.
Later after I quit hotshoting I upgraded the truck to be a sport car so the turbo and tranny Put in gauges for every little thing. Soon I went and changed my fuel pump. I wasn't getting constant pressures.

When I added the edge chip I was getting around 21mpg city.

 

do not get 4.10's you will regret it!

I absolutely hate my 4.10 gears...I would trade for 3.55's in a heartbeat.

if you want big power, buy a built trans like DTT or goerend, etc..

otherwise a billet torque converter, input shaft, and a valve body goes a long way...

gauges are a must for any truck..
your truck would do good with a rail pressure gauge, EGT, Boost, and trans temp gauge.

I second the airdog or fass lift pump with filters...go with a 150GPH or higher pump for a CR truck.

as for both mileage and/or power..."EFI Live" is the only way to go best CR tuner out there.

 

Thanks for the input. I haven’t really researched this but I am assuming dieselsare the same as gassers and are sent from the factory with dino oil. If that isthe case do you think me changing everything to synthetic will cause moredamage that good?

 

I run synthetics in my engine and trans, and dino in the PS fluid, and currently in the rear ends as I haven't changed fluid in those yet...

if you decide to go synthetic: I recommend AMSOIL. best stuff out there.

otherwise you can stick to dino oil. valvoline 15w-40 dino oil is actually the oil that is officially recommended by cummins.

I run AMSOIL 15W-40 Heavy-Duty Diesel and Marine Motor Oil.

You order it right from their website.

I have an account with them, so I pay less then the price shows...getting an account with them pays for itself with one oil change..you actually save like $10-20 paying for the account due to oil cost savings...

I usually buy a 2.5Gal jug, and a couple extra quarts to make up for the 1qt extra it takes (11qts) and for my oil leaks months later

 

I have always used royal purple and have never had any problems, but that was in gassers. Is there that big of a difference, when talking fluids, between gassers and diesels?

 

yes: diesels can go a LOT longer on an oil change than a gasser can

diesels do not break down their oil near as fast...you can change engine oil every 7-10k miles in a diesel with dino oil, or every 15-20k miles with high quality full synthetic oils.

as for oil weight...stick to 15w-40 diesel rated oil in your cummins... don't run any heavier or lighter than that.

royal purple is fine too

as for your automatic, make sure you run ATF+4 (all brands of +4 should be synthetic)
quart overfill helps a bit.

 

good to know. thanks for the info.

 

What trans is it? Need to pop the hood and look at the engine ID tag and see what the power rating is. For the most part, these have an unwarranted bad reputation. Anyone that says they are junk, go ahead and forget anything they've ever told you

A programmer that changes timing will likely increase mileage, but you aren't likely to see much more than 21 or so. Add a 4" turbo back exhaust to let that puppy breathe a little better.

With 63k on it, nothing.

Does it have the in-tank retrofit lift pump, or is it still on the block? Look under the fuel filter towards the rear and see if it's there. If it does have the in-tank retrofit, save your money, you don't need a lift pump.

I see no reason at all to change gears in the axles.

As far as synthetic vs dino juice, that's up to you. I refuse to waste money on a name with Amsoil, there's cheaper stuff that's just as good, and FAR easier to find in a pinch. I hopped on the bandwagon once, never again. Not sure where this myth came from that it is somehow superior to anything, but it's false. I hear good stuff about Royal Purple.

For the trans, just get a drop in unit from Goerend or Garmon.

EFILive isn't available for 03, Smarty is the ONLY one you should run.

Gauges are nice, not needed on a stock truck. A good option is the Edge Insight CTS