OEM Sachs do not last like you would think. The post about 80-90k is correct. I did mine with new Bils. HDs at 140k, and 3 were leaking. I realized after changing them that, aside from the stiffer ride with the HDs, some general shock-dependent ride characteristics were corrected, issues that I had experienced since - you guessed it - about 80k.

I should have done them 60k ago. They weren't horrendous, but new ones made me realize what I was missing

I might add that I didn't think the rears were an issue like the fronts, but the rear sits an inch higher now, and looks like it should. They were obviously failing.

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL