Unfortunately the guy answering the phone has certain rules he has to follow because of legal issues. So he has to state use the oil spec'd for your engine, or lingo along those lines. Take that same question and ask him at a bar having a few drinks and he'll give you the answer you're looking for. Shell is great and I have used it for MANY MANY years in everything from my hotrods to boats. It has friction modifiers in it and I have even used it on my motorcycles.
I know it can have more detergents to clean diesel engines and their additives are specific for low RPM high load engines. Older diesel oils were popular because of the additives that they had while newer diesel oils have less of since diesel emissions passed for 07 model year. New diesel oil are safe for cats but do not have that good old additives they use to have.
New oils are good for anything you want to run them in, especially our older motors!