Okay I will start with some history on the car. 2002 A6 2.7T with about 97,000 miles, I do have an oil leak on the valve covers and cam seals. I had the timing belt replaced about 800 miles ago. I have 5W-40 oil in the engine. (The parts house did not have 0W-40 oil in a full synthetic) and the owner’s manual said the 5W-40 will work). The weather has been cold the past few days, this morning was -4F to -7F.
I started the car but did not let it idle like normal only 2-3 mins and drove to the gas station and the car was putting out a lot of exhaust (I think it was because of the cold engine and low ambient temp) I get on the interstate and watch my exhaust and it seems to clear up. Then the low oil alert (yellow) pops up on the dash. I think I may have lost some oil due to valve cover leak and can add some oil when I get to work. A few miles later the low oil warning (Red) pops up, so back to town I go. Pull into gas station I open the hood and I can hear the lifters and other noise shut the car down and check the dip stick and no oil I added two quarts of oil check the level nothing shows on the dip stick. I look under the car and I see oil dripping from the back of the oil pan on to the sway bar (I think). Add more oil and start car so I can drive it home. I also have check engine light I pull the codes and I get Code P0012 Camshaft Position Actuator A-Bank 1 Timing over Retard and P0134 O2 sensor circuit no activity detected.
1. Does the Cam Actuator use oil pressure to change cam timing? If yes then I can ignore this code.
2. Would anything oil related cause the O2 to stop working?
3. The Big question is there a oil line/seal/sensor on the back of the engine that would be able to dump all my oil out?
I will do more searching on Google and this and other forums as I get time at work. Any and all help is appreciated.
THANKS

 

Looks like I had a frozen PCV system. Once I got rid of the blockage I took car to work removed the PCV/spider flushed the sluge out and dried all the tubing. Also made sure all the ports where clear the one going to the block/crankcase had the most stuff in it.