My vehicle is an '03 A6 3.0 engine with 160K miles.
I have been using 5W-30 oil in it.
I have been getting intermittent oil pressure warning on the dash. It is the red oil can and it beeps three times then goes away. I just replace the oil pressure sensor to see if that was the issue but I guess not. It takes about 20 miles or more for it to activate the warning, then it will go on and off with no specific duration. When the warning sounds, the vehicle is stopped, then restarted and it seems to be fine for a while. The light never seems to stay on, as after the three beeps it turns off and no indication on the dash. I've read about the o rings at the oil pump being a probable cause for pressure issues. Does this sound like the case? Where are these o rings and where is a good place to order them from? Does the pan need dropped to get to these rings? How many are there to replace?
Is 5W-30 oil too light for this many miles? If so what should i use?

 

There is a TSB on this problem, TSB 171006. This calls for a pressure check, if low, checking the oil pickup for blockages, then replacing the 4 O-rings on the oil pipes and the O-ring on the pump drive chain tensioner. Also check for leakage at the cam adjusters. If this doesn't do it, you remove the intake and go to the oil check and spray valves under there and their pipe O-rings. Just get the TSB and read it to knowe what is going on. You can get it and repair info by subscribing to Alldata.com.