Some believe that if it's good for gassers and Diesels you shouldn't use it on a Diesel. Use Diesel specific products only.

Not sure of the benefit of upper cylinder lubricant in a MB Diesel since the side of the intake valve that would benefit from lubricant never sees fuel. I doubt the lubricant would survive combustion so it won't do much for the exhaust valve either.

Are you thinking of something to pour into the fuel tank or something used directly into the IP like Lubro Moly Diesel Purge?

Sixto
87 300D