I topped off my power steering in my 1980 245 with regular "power steering" fluid. The manual and Haynes, I realized later, call for automatic transmission fluid. Does it matter? is PS fluid really just ATF fluid?

 

Same thing. Don't worry about it they are exactly the same. If it starts acting funny you might want to drain it and put in 100% of one or the other i'm not sure if it's bad to mix them but i highly doubt it. As long as the power steering is working fine you have no problem.