From what I've searched/read here, true the pump is lubricated by the engine oil. The main concern is the rubber seals in the IP that come in contact with the fuel not getting enough lube and tearing causing the pump to leak.

Wish I could give you the links but I don't know where I read it.

I've always run conditioner in my diesel just to keep the system clean. Just so happens there is lube in it too. I realize there is more expense involved but I've run it in my diesels for years and never had any fuel related problems. Also less smoking. Recently I bought an '85 300td and right away started running Power Service in the fuel. Over a one month period my mileage went from 28mpg to 30mpg I think due to the system being cleaned out=better running car=more mpg.

I'm no expert, just reporting my experience!

Cheers,

Bill