blowing out oil

What is the serial number prefix. If it's a 2ws or 1lw with the breather coming out side of the block then it's quite normal after being worked hard at high boost levels for prolonged periods. If you want to fix then you have to get a breather off a older e model or newer 6nz that's in the valve cover. Then just plug the one on the block. Cat will sell you the upgrade kit, I've never priced it out but I'm sure it's way too much. Better off going to a truck bone yard and finding what you need.

 

I have a 1lw and a 2ws. They both do it. Nothing wrong with the engines.

 

That's not too bad I guess.
There's a technical service bulletin on the issue , I've seen it.

 

First off you want to have them go into the programs, the Parameters and at the bottom tells you the oil pan capacity, they are famous for having too much oil in them, some up to 53 quarts, where it should be 32.
You want to preasure check the turbo for passing air past the compressor to the crankcase, the valve guides are also a weak point, leaking air into the engine.
If you decide to add a vent to the cover you do not need to remove the other vent. Be sure the vent hose you have is clear.
Just a thought!

 

A second breather would help or even just moving to a rocker mounted breather by itself may cure the issue.