I put valvoline max life red cap atf in my 67 f250 power steering after a pump replacement. It seems to have more consistent power steering whether cold or hot, but like I said, after replacing the pump. Haven't had any more leaks or anything. I'd recommend going that route. On my 69 ford ltd, I siphoned the reservoir and filled with some mmo to help flush the system a bit after I bought it. Car had been sitting a long time. After a couple months but not many miles, I siphoned the reservoir maybe 5 times after driving it until the fluid was all clean. That one I just used regular type f and it's fine, but more expensive. And I think I got better results with the max life atf.