General discussion1

General discussion2

General discussion3

Gil Baumgartner oil study

Multi-viscosity oil clarification

Why to not use diesel oil in a gasoline engine

ZDDP

Performing a search will bring up a bunch more.

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If a zinc additive is required, my personal preference is ZDDPlus. In general, the smaller the bottle or the more concentrated the additive, the better it is as that reduces the amount of base stock oil that’s included with the additive. I’ve used the GM EOS in the past but have not seen the zinc/phosphate amounts in that particular additive since it was brought back as a new part number after it had been discontinued for awhile.

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And here’s a word of warning about zinc supplements. Adding additional zinc in the form of supplements where the oil already has the necessary amounts overloads the oil with too much zinc and that by itself creates other issues including cam lobe pitting. Read the API bulletin for the SN oils that still retain the required amounts of zinc for the older engines. Once the appropriate SN rated oil for your application is chosen, you’ll find that using supplements or oil formulated for diesel engines are not required. And let’s add this: Starting with the SN classification on the oil, many of the diesel oils now have reduced zinc amounts.

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Here’s the link to the article that was recently published in the Y-Block Magazine that goes into more detail on the variety of the reasons for cam lobe/lifter tappet failures on flat tappet camshafts. Engine oil by itself is only one of many considerations when taking into account the multitude of other reasons for cam/lifter failures.

Camshaft and Lifter Failure Causes