Blue_diamond it sounds like you are having the same issue I am having. Precision has a PDF that they sent me with Instructions of all the do's and don't's of installing their turbo. It discusses the need for good ventilation whether you do vta or not.
If you do not pull air from your intake or exhaust then you need to have large enough hoses and filter for the crank case and heads to breath. Otherwise pressure will build in the crank case and the oil will have trouble draining and push out of the turbo. I think in my case the really long hose from the AOS to below my car may have been restricting breathing causing this form of oil loss.
If you do connect to intake you have to try to eliminate the sucking in of oil. Since you are creating a vacuum in the crank case there shouldn't be an issue with oil return from the turbo. This is where I am at now. The 6466 probably sucks so hard that it pulls oil straight through the AOS. This is why I want to put a second baffle system in to try to minimize the amount of oil that does get sucked in. It is bound to happen but I think it is better than being pushed out the turbo.
If I am getting to much oil sucked out then I may either do scavenge from exhaust since the suction from that should be much less than from the intake. As long as there is negative pressure in the crank case it should be good. Or I will do two vta cans with big ass filters.
I have pics of my turbo from last night ill post. I also felt oil on the Intake side. It was a small amount but I think that is from the AOS being sucked in. One more side note. I finally cleaned my air filter while I was checking everything else. It was filthy. I read that a clogged inlet could also cause oil to push out of the turbo. Hoping this helps my oil issues.