In addition to the loud power steering whine and whirring this car has had, I notice that the oil pressure gauge fluctuates downward whenever turning the steering wheel. Any ideas as to what can be causing this?

Could just be a bad oil sensor. How far does it move? It will go down a little if the RPM drops.

My dad'* pickup truck has the same thing, loud whining and the oil pressure drops like a rock to zero and wobbles. The mechanic said to use Lucas Oil Stabilizer (to thicken the oil) but a single bottle only makes the wobbling less violent, and the members on here say not to use it because it makes bubbles. I'm also interested to see if you fix this and how.

I think Dan tagged this one.. You turn the wheel..the poor pump is drawing power and pulling rpm'* lower.