FLE going way overboard w/ this ATF specification for our p/s systems.
a p/s system don't care whether ATF is dextron 3,4,5,etc...or whether
its type F, OR whether it's dino or group5 synthetic. All it cares about is whether it's a hydraulic fluid and whether it's within a range of viscosity to not exceed or not provide a set psi when the p/s pump's under operation.
You can use walmart atf and it will hold up everybit as well as the top of the line ATF like Redline, Amsoil, Pentosin, etc.... b/c in a p/s application, there is hardly any heat generated....nothing even close to the type of heat generated inside an auto trans. So ATF in a p/s do not break down. it only gets dirty.
The most important thing, therefore. is to keep the ATF fluid clean. Thus, using walmart ATF, and changing it out every 20k miles is alot better than using Redline/Amsoil/Pentosin ATF and changing it out only when required (such as when there's a leak or a hose replacement).