cold weather and color of oil

[lair116]

I have a question for you lightning owners, I have a 04 lightning and have no choise but to drive it back and forth to work and in the last few weeks it's been in the 0's and in my sight glass on my oil seperator the oil has a differant color, like light brown (milkey) and I also noticed it on the bottom of my oil filler cap like if theres water in it, i checked the oil dip stick and there's no signs of water and the oil is clear and normal, I had a K&N oil breather on it which made my check engine light come on all the time and the codes on my preditor tunner says that it's running lean so I took it off and put the stock oil cap back on and since then there has been no check engine light come on and noticed there's a lot more power, I think that when I had it dyno tuned they forgot to add the K&N oil breather to the tune, I'm thinking this would be like opening up a vacume line which would make the motor run lean has any one come accross this? thanks, lair.