I did a road trip from Chicago to Orlando and came back on 7/21/14 on the way back my car warned me about low oil, so I put more oil in it and checked my dip-stick until it was good to go. Now on 8/02 I had got this warning light. on 8/04 I checked my oil and topped off. I was planning on getting an oil change this week but I want to see if this is a bigger issue than I thought.
I read a few forums, and someone did say after an oil change, their car turned out to be fine. Someone else said that their warning light came on after 2k rpms. I noticed that if i drive normal the light would come up within 5 minutes of driving. But on my way home from work I decided to go slow, and shift under 2k rpms, and keep it under there. With me driving like that, I noticed the light didn't come back on until 15 minutes of driving on the expressway.
Does anyone know what my problem might be, I am extremely low on funds, because of this trip and bills, so I cannot afford for Audi to inspect the car and charge me an arm, leg, and my 1st born. I have a 2006 Audi A6 4.2 S-Line with 165k miles on it.

 

It's rare, but your oil pump might be giving out, or it could be clogged up with sludge??

You would need to get the pump pressure tested. there should be a port that a mechanic can hook up to to check this.

 

make sure your oil change includes the filter, the sludge up fast and that will create low pressure and the light will come on.

also the sensor in the pan is known to go bad, its an easy repair.

 

I had the same problem on my 1.8T. But mine was when it is under 2000 revs.
It is the oil pick up in the sump. Its a very fine gauze and will block up easily. To change this the sump needs to come off, and to be honest. If you're in there it is easy to change the oil pump and pick up in one go as they're bolted together, and a fairly cheap item on eBay.

However its a weekend job, as the sealant used to put the sump back on with (as it doesn't use a gasket) needs 24hrs at least to cure.

Good Luck!