Dear Tom and Ray:

My father used to buy Automatic Transmission Fluid and use it in the power steering reservoir instead of Power Steering Fluid. He said it was the same stuff, so it didn't matter. Is he right?
Frank

RAY: He was. But he's not anymore. They used to be the same, but that changed about ten or fifteen years ago.

TOM: Around that time, Automatic Transmission Fluid started getting more complex, and now it has materials that are not recommended for your power steering system.

RAY: And likewise, Power Steering Fluid today does not have everything it needs to serve as modern-day Automatic Transmission Fluid.

TOM: On the other hand, we have noticed a striking chemical similarity between Automatic Transmission Fluid and our mother's borscht recipe. I'll think I'll try it in my brother's car tomorrow and see what happens.