Gen 4 Engine Mystery blown head gasket.

I like these too. They are easy to use on most used cars i go look at as well. If you pass this too, more than likely you may just be getting oil dilution from blowby. Blowby contains water, unburnt fuel, carbon, etc... So thats how you can get milky and frothy catch cans.
If thats the case maybe its just a quirk of your new engine install. Clean out your froth and go for a nice loaded interstate drive and see if you can burn off the rest in the oil and if your froth comes back. But it doesn't sound like oil dilution. You could also change the oil as it wouldn't hurt.

 

I believe that tester detects carbon monoxide in coolant system?

 

yeah it sniffs for exhaust in the cooling system

 

Not sure what those are. These are what comes to mind, but don't think you mean them:




Do you mean the main cylinder head bolts:


Just realized I'm responding to your way-back-when initial post. Maybe disregard.

 

Yep, that's what happens when an engine operates with no fresh air flushing blowby gases (notably including water vapor) from the engine. Your blowby was forced to exit via the hose that normally supplies fresh air. Do you see more "mayo" around the throttle plate?