I have a 97 3500 that is using a lot of oil ! Like 8 quarts every 100 miles , no **** !
It has 292k on it . The PO removed the fuel plate and jacked with the star wheel . I put a 100 fp in it and have bin working the wheel back a few clicks at a time . No egt gauge or boost so I'm just trying to get it good right now but it just started drinking oil at a alarming rate .
The exhaust was full of oil so I assumed turbo. Took it to a shop and they said intake ( cold air ) was clean but turbo wheel was sloppy but not much blowby so I had them put a new turbo on .
Drove it 190 miles and had to add a gallon . Drove it to work today and put it was slitely below add , 3 quarts in before I left for home , a few miles from home my oil lite came on and pressure dropped . Not a drop of oil on the dipstick.
It starts pretty easy in 20* weather so I wouldn't think it's rings so what else could it be ?
It doesn't leak any idling for 30-45 min .

 

That is quite odd. Check that your valve seals have not popped off and ridding up the valves. Not that I suspect that it would burn that much because of that but it could account for it. Is there a reason it idles for 45 min? If your idling all the time, especially low idle you could be washing the cyls and burning oil. there's not many places in an engine to burn oil through. Valves, rings, turbo, crank ventilation could be plugged. Which would show up with blow by. And leaks. 12v are super common leakers. Rear main, tappet cover, valve cover gaskets if old, front cover, oil pan.

 

Super common leakers, not so super common drinkers. This is unusual to an extreme degree. How's it smoke? If it's burning that much it should be horrendous, unless you're running synthetic which, at the rate it's drinking it would be... prohibitively expensive I would think. The 12V is particularly well suited to run on motor oil so, not much worry on that front, but running it dry is more problematic. I have never heard of one going through oil like this that wasn't leaking it. Hell, even one that was leaking it. Are you sure it doesn't leak? It wouldn't necessarily be that noticeable while idling, most of the leaking in these happens while it's working, due to the ridiculous amount of crankcase pressure they make under boost. Of course, there would be ample evidence all over the place if it's happening. I can't imagine how it could be burning two gallons in 100mi and not be running like crap though. This is perplexing.

 

ya it is very strange. it must be leaking it or you'd have crazy amounts of blow by at that rate.

 

Seems like it would be smoking like a bastard at least.

 

Only smokes when I want it too . Runs really strong . Only let it idol cuz I was using it to jump my car .
I have no idea what to do with it now , sell as is , take it back to a shop but my wife says no more money in the pos . I rebuilt the front end from ball joint to ball joint with new box and everything . New shocks , 6 new tires , new exhaust with a muffler. New trailer break control, breaks .
Can a guy rebuild without pulling the motor ?
Is their any kind of vent to the intake side I could be missing .
The PO drilled and tapped under the oil fill and put a 90 and s hose in it , why ?

 

If you're dumping that amount of oil in and it's going out at that rate, it will show where it's going out. If it's not leaking when it's idling but only at highway speeds then you'd have gallons of oil under your truck and it would show on the ground after you parked.
If it's burning that much, you'd probably see smoke and have it leaking out of your exhaust. Simple answer is that if you're dumping that much in and it's going away in a couple hundred miles then look at the exit points...leaks and exhaust.

 

I'm no expert...drilling and tapping the oil fill?? The only rationale I can think
of is a vent.

 

ya i assume its leaking. no way it could be burning that without a ton of blow by or the turbo which you said is new. there should be a way to tell quite obviously. my previous engine had a groove in the cyl walls in one direction and had a ton of blow by and i might have burnt a litre every 800km or more. you must be leaking it. the hole is probably a vent. kind of sounds like the po was an idiot. which is unfortunate. not sure what to say with out looking at it. personally unless the block is toast id never toss a 12v away. they are extremely robust and don't fail often so i feel as if your looking past something

 

When you have time, when the dipstick shows it's low, drain it and see how much is really in there.