2009 386 Peterbilt problem (Need Help)

A picture would be very helpful. Of the tank and the fluid that is coming out. But at this point if every thing is easy to get to ask her to take the main air line off of the compressor hold a piece of card board in front of it or where that line would normal be and run it for a min or two and let us know if it's getting oil on it or not.
The constant regens with out a dash code is odd. But if it's not air pressure related have her change the DEF filter. About 25 to 40 bucks and ten mins. Paying close attention to the fluid color and texture. And then taking off the doser value. And before cleaning the nipple end blow air thru it. Making sure to blow it away from her.
Then cleaning the black spoot off of the tip. How if there is a lot of spots on it. Take a metal coat hanger and stick it in the hole that the sprayer sprays into and wiggle it to free up any thing that could be in there.
Another but kinda unreliable test is to try and see the fluid coming out of the tank when she drains it. I am not familiar with the Peter system. Nor am I familiar being the air helping the Regen. I am how ever very familiar with oil coming out of spots thats not supposed to.
And sometimes just dirty crusty yuck that looks like oil. How often is she regening. It can only be a handful of things. The reason for the air compressor test is to see if her truck is passing oil or if the compressor is leaking oil. After the engine cools 10 hours or better have her open her radiator cap and let us know if there is pressure in the radiator.

 

If the 3rd tank is a air tank there will be air lines going to or coming from it. Tanks have bigger air lines kinda hard to miss. Have her crawl under it and look if she has to. It will have something coming from it. Air lin. Hydrologic line or wires