bigeyes

2000 A6 2.8 engine.
Recently replaced timing belt, water pump, idler pulley, tensioner and pulley, thermostat .
At the same time I replaced the air pump line, the PVC lines and valve.
After all work was completed engine ran well, However, after running for about 15-20 min. the oil light came on. I installed a mechanical oil pressure gauge to determine if possibly the light was malfunctioning ( it was not). When I started the engine I had between 65/70 psi after about 15-20 min. the pressure had dropped to less than 5 psi at idle and would not recover at higher rpm.
I changed the oil (10w-30) and filter and tried again, this time oil pressure dropped to 18/20 psi at idle and maintained about 40 psi at 2000 rpm.
While driving the car on short trips (3-5 miles) to see if it would maintain these pressures the front crank seal began to leak very badly. I had the car towed home (rollback) and replaced the crank seal, started the engine and the new seal leaked immediately(as bad as the old one). Any suggestions that would point me in the right direction would be appreciated