using deisel motor oil in old engines?

[chargerjy9]

 a little background: 73 Charger with nos matching, never been messed with 400 4 bbl motor.15,000 miles on it.

a mechanic tells me that  I should use 10W40 motor oil for deisel engines. he says that todays modern oil lacks many additives  ( zinc, etc) that oil from back in the day had; and that these older engines need that stuff. deisel motor oil still has all these additives.  he says that running todays oil in my car is a recipe for disaster. engine could seize,etc,etc.

any one out there can confirm this, does his rational sound right? I never heard this before so I am looking for advice.

[BrianShaughnessy]

Up until a couple years ago diesel oil was the ticket.    Then it got reformulated also.

Did you read the sticky thread?  http://www.dodgecharger.com/forum/index.php/topic,46015.250.html    Probably not.