In Texas, we have no idea what cetane level diesel fuel we're putting in our MBs, they don't post them on the pumps like I observed once in Maryland. So just for the heck of it, I purchased a bottle of Power Service Diesel Kleen, and poured the whole 16oz bottle just to see how it would work. The car ran smoother, no smoke, so I gave it one more whole bottle treatment. Some three to five months later, it still runs smooth and smoke is at a minimum. It's been a while since I've used it, so I will probably add some if the running gets rough and smoky.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.