Dd15 oil leaking From breather

Oil in coolant is usually a bad oil cooler. Cooler gets a pin hole or a crack, oil pressure being higher than coolant pressure, pushes oil into radiator/ coolant system. New cooler, along with a good flush ( probably 3 x ) using cascade, or Ajax dishwasher soap,(low suds) till oils gone. I had one go bad on my last Truck, didn’t realize at the time it had a minor head gasket leak. The pressure caused the oil cooler to leak, right at a weak spot, a small manufacturers defect, or installation damage, at a small dimple on one of the oil cooler fins. Eventually I was adding more coolant, and realized I had a head gasket, or cracked head. Not before replacing a leaking Waterpump also. The pressure attacked the already weak points. Coolant should never need topping off, once it’s full. You can tell if it’s under too much pressure, once it gets bad. Getting the coolant pressure test, will catch a small leak, before the head gasket blows, and leaves you stranded. Get it checked, might be pushing coolant into crankcase, causing steam from the vent. Easy diagnosis at any Shop. They can pressurize the system, see if it holds. Probably won’t, if oil coolers leaking. Then they start the Truck, and watch if it builds excessive pressure in the system. If so, you’ve got problems. If not, probably just a bad cooler, adding oil pressure into the system, along with oil, adding to crankcase pressure, and maybe that crankcase filter someone mentioned? 1 hr Labor charge tops. Rule out the worst case scenario, before jumping to $$$$$ conclusions.