I used that universal filter on my '83 300SD when I put in a new compressor. It did not suffer black death - the bearing was just squeeling. I can't say it has really protected anything but it sounded like a good idea. I also thought it may help me with any warranty issues.

I spliced it into one of the hoses (in the straight metal portion of the hose) by the ac drier. However, I had to make the ID of the compression "ring" a bit bigger because it would not go over the metal line. Otherwise it was easy to install.

Richard

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Richard
'83 300SD 180k
'87 300SDL "200k"
Central Ohio