Audios13

Hi, I have a 2006 S4 with the 4.2. It recently had the oil pressure light come on. I did a full oil change and knowing it has a very small almost non existent leak from the oil pan I added STP oil treatment and stop leak and proceeded to put a new oil pressure sending unit on it since it's common for them to go bad and the plug was full of oil. After doing so it ran fine and showed full of oil. Next morning I check the oil before leaving and it shows completely empty and is running as so but it doesn't appear that any has leaked out. Does anyone know if its possible that the thick oil treatment fluid could be causing this? I didn't want to run it long enough to warm up to find out since the motor sounded like it had no oil in it and I was now late for work at this point.. Any advice or insight would be appreciated