I don't think anybody has ever questioned extra lube is good. The question always ends up about benefit vs cost. I have not seen the cost keep up with the benefit.WHEW! Thanks! Cummins, Cummins,Cummins. I say, what does Bosch say? Most anything can benefit from extra lube!
Now days we see many less physical failures with the vps since bosch figured out the up grades that were needed to make them live a normal lifespan. The p7100s just live for ever normally,common rails die from too much pressure or contamination causing early deaths. When it comes to mileage claims they are just that claims... . cetane improvers can help but I have not seen any yet that pay back