I just used Mercon V on my 91560SEL. I have a flush machine at work which is a big help and an easy process. So far after 1k miles, no problems and no leaks. Since your vehicle is newer, I would suggest using what MB recommends. If there is no special fluid MB recommend then trans fluid or generic power steering fluid should be ok. Does your vehicle come with a p/s filter? change that as well

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2001 E55

2001 E320 Sedan

2001 Subaru Legacy

2006 SLK280

2016 Subaru Outback 3.6