Wombat wrote:

You mentioned there was no problem prior to changing the engine oil, just wonder if a problem with grade or type of oil?

Wombat

he did it even before, then I changed the oil and filters hoping for the best

Good candidate for an engine leak down test.

Vecchio post del magnete=229654 id utente=632Buon candidato per un test di tenuta del motore.

hello, what do you mean?

      
l'olio è sul bar arrivato in add. era a pieno livello.ha mangiato quasi tutto l'olio nelle prove volevo solo sapere se togliendo la coppa dell'olio riesco a togliere tutti i pistoni e i cilindri

Similar to a compression test. You place each cylinder at TDC, valves closed and supply compressed air at about 90 psi and listen and observe where the air is leaking out. Good check for ring/liner condition, valve condition, cracks in head or block plus liner projection sealing. Doesn't do anything for checking valve guide wear though which seems to be one of your contributing factors.
If all checks out you may just have a case of slobbering where liners become glazed and affect ring sealing.
Typically not severe when engine is just started and cold but worsens as engine comes up to temperature.
Sometimes putting the unit to hard work will recover the ring sealing.

Is the Bon Ami treatment used anymore?

Have you actually worked this crawler yet, or has it been sitting in your yard just idling away for hours, which is the worst thing for them, that black "oil" sure looks like slobbering to me, I'd be putting that tractor to work for a day, get it hot and run it hard, like it was designed to do.

If after a days hard work you still have the slobbering, then start looking further, my old RD6 will cover me in black oily Cat pox spots out the exhaust if I let her sit and idle for even 30 minutes, but once I get her working and really warmed up, it clears away quickly, you will see the smoke coming off the exhaust manifold as it gets nice and hot.

Try all the easy fixes first before tearing into the motor, Cat engines are designed to run flat out.

Update
Hi guys .
I used the crawler loader hard today.
Here it is beastly hot, the converter has remained in the green and the coolant in the green. The engine is fine, no revs drop and digs a lot, no smoke.
The problem is that the 4 hours ate 10 liters of oil.
After 2 hours I turned off to check everything. I turned it back on for another 2 hours maximum and loading and pushing trees. I still used it hard.
Tonight I check oil and notice that it is way below the add sign.
No leaks from the exhaust, perhaps at full throttle it can burn it and does not have time to come out of the exhaust.
I'm embittered .
I would not like to open an engine that is running very well.
At low revs, blue smoke comes out halfway through the accelerator and gives intermittent coughs, like pops. At full throttle it's great
I do not know ....
If it were valve guide would it do it at all revs?
blow by and completely absent, beyond belief

Sadly, to burn that much oil in a day sounds that engine needs at least a new set of piston rings, and maybe cylinder liners too, depending in how worn they are, and once you remove the cylinder head, you are crazy not to recondition it too.

At least you tried the easy fix first by giving it a good flogging, but 10 litres of oil in 4 hours is a lot, my old RD6 which has a 9 litre diesel engine, will burn about 3 litres of oil in a 8 hour day working hard, and I know that engine is very worn inside, because I removed the engine head a few years ago and could easily see the top piston rings when looking at the top of the piston!