Its not a bad idea to flush it every 100k miles.

I suck the resivor dry with a turkey baster every spring and fill it back up, keeps it clear. I like to be able to see the filter I'll flush it again in a few years the car doesn't get driven to much anymore.

I use MB brand PS fluid, its a bit pricey but my pump started to whine with the aftermarket stuff.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200