I switched to valvoline semisyn and it quieted the rear end down nicely on my '73 280 SEL. This product also comes in a convenient squeeze bottle that you can get up to the fill plug without using some kind of pump.

Gotta do this on my Diesel 190D 2.2 soon.

Sholin

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What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.