The Star magazine (by MBUSA; vol. 57, #5, Sept.-Oct. 2012) has a pretty thorough article on this subject on p. 54, entitled "The Weighty Subject of Oil for Old cars", by Richard Simonds under the contents heading, "Classic Tech".
It seemed to me to be a very good article, and one topic heading ("Reading the Labels") is a big help in understanding the API codes, as well as providing background and context for judgements on additives in general and ZDDP specifically.
The entire three-page article is well worth a read, I think, and had me underlining passages as if in a textbook. I figure this article paid for at least a couple of years' membership/subscription dues to MBUSA.
[All that said, I have a nagging feeling that there's a one-letter typo nearing the end of the first paragraph on p. 55. It's not the sort of thing a spell-check program would catch but is of significant relevance if it is indeed an error. Whaddayouthink?]
Michael,
You're conversant with the editorial staff; is there something here that merits making inquiry of Mr. Simonds? Or perhaps Ms. Hislop, Copy Editor, with a courtesy read-in for the author? Vice versa? [In any event, our appreciation for the articles' considerable overall value should surely be emphasized.]
