M11 problems

I have a truck with a m11 it’s a regular celect. It was a 310 and I had it reprogrammed to 370. It’s always been a dog. A couple months ago I took it for a roughly 600 mile trip and used roughly 3 gallons of oil…probably burning some but I think most of it went out the blowby tube because it was leaving a paper size puddle in the time it took to put fuel in it. The truck normally does local work with dump trailer and a lowboy. Fast forward I let a friend use it to finish a delivery after he blew an engine and ended up renting it to him and he’s putting a couple thousand miles per week on it. But the crazy thing is he’s using less than a gallon of oil per week. I also find it interesting that it now runs like a scared monkey (relatively speaking…it’s just an m11) I personally think he found someone to program it but he denies it…I really don’t care but am just happy it’s doing good for him.
so the question is how can the oil consumption go from a gallon for 200 miles to less than a gallon per 2000 miles. The engine has roughly 200k but around 30k hours ( it was a concrete mixer). And I realize it’s near the end but just curious on anyone’s input on the oil consumption situation.

 

I haven’t specifically asked but it seems like it’s always been mobile delvac jugs in the truck when it comes back for weekly service. Which is probably what I had in it…or could have been rotella but all 15-40.
I wonder about the rings sticking…..

 

I would guess he’s idling less and probably not running it as hard but I don’t know. When it idles here for any length of time it’s usually running the hydraulics on the lowboy which is a noticeable load because of how restrictive the plumbing is and it’s a decent load when the winch is used.

 

Does yours actually run good???
That’s almost got to be him, should’ve been a mac wagon though #### close on wheel base it’s 252 by the door post. Probably shingles on the deck but idk I pretty much let him do his thing as long as I get my money at the end of the week it’s all good.