With the DOT 5 or DOT 5, I think you are actually refering to Brake fluid.
I think he is as well. Power steering fluid is just hydraulic fluid. Since mine leaked from a bad hose I bough it by the gallon from my John Deere dealer. It is all ten weight mineral oil. Even the tranny uses it, but ATF has a red dye in it to warn you that you not only have a leak, but what is leaking, compared to all of the other oil leaks old Chevys have.