The service manual says to use automatic transmission fluid in the power steering. How critical is it to do this instead of using power steering fluid?

Searching the internet, it sounds like systems that use ATF are designed to a higher standard. They'll withstand higher heats involved with using ATF. Systems designed for power steering fluid require power steering fluid because they would have trouble using ATF due to higher heat. So, it sounds like power steering fluid operates cooler. I read a few reports that people who had PS leaks fixed their leaks by replacing ATF with power steering fluid.

Anyway, wondering if anyone here knows.

Thanks,
Mark

The manual and the PS resevior cap say ATF for a reason.