Thanks for posting this info Gary. The presentation provides an excellent background for the development of modern engine oils and explains what is involved in engine lubrication.
I have some problem with the "absolute" statements concerning what will and will not work but allow that the author was attempting to convey his own beliefs. Specifically, before I retired I had several conversations with product engineers from several major engine oil manufacturers as well as several engine oil additive suppliers about the suggested oil to use in my 66 230 SL. All agreed that the use of a CJ4 15w40 Heavy Duty Engine Oil would serve my purpose very well.
To address your specific comments:
ZDDP is one of the most commonly used anti-wear additives for developing engine oils. Be advised that it is not the only additive available and, as technology improves, I suspect at some point it will be improved and / or replaced. ZDDP levels by themselves do not establish the feasibility of an engine oil. The most consistent way to insure that a motor oil has wear protection is to check that the product meets industry standards for wear when tested as part of an overall approval system. The only API products that are currently tested for wear as part of the approval process are the "C" grade heavy duty engine oils. The latest approval being CJ4. There are many ASTM tests that will indicate wear and or presence of ZDDP but, in my opinion, the API tests are the "gold standard" of the industry (at least here in the US) and I use them as the basis for my comments.
20W50 viscosity grade is not for everyone. As I noted in an earlier post, depending on the pour point of a specific product, a 20W50 engine oil may not provide adequate lubrication at cold temperatures. Please note that all 20w50 oils are not created equal so the real answer to the question, "Should I be using a 20w50 engine oil?" is "It depends on technical specifications of the product you are considering and the typical operating temperatures you will encounter in using your vehicle." You should not conclude that a 20w50 engine oil suitable for use in warmer climates will be suitable in cold climates. (Example: Texas vs. Canada)
As an additional note, the choice of engine oil, while important, is not a "simple" decision (as noted in the plethora of information that is offered on this web site as well as many other sources) Engine specifications, product specifications, engine mileage, environmental conditions, financial considerations and even emotions are a part of what may be right for you.
For me, a HD 15w40 with API CJ4 approval works just fine.
Norm