While researching available parts for my '80 300SD, I keep coming across a power steering filter. I have never heard of such a filter. I once saw a picture of one. It appears to go in the resevoir. Does anyone know how to change this out? While I am asking, how do you change out the power steering fluid, which apparently is recommended from time to time. Also how much does she hold?

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member