In rebuilding my 82 4x4 I have found some great info on the type of oil we should be using. Any old fashoned oil with Zink. Most modern oils do not have Zink in them anyone. This causes severe wear on internal parts especially on cams and rockers. And most new oils will not blend well with a Zink additive. I'm switching to a diesel truck oil like Rottela as it still has Zink.

 

For what it's worth, I am currently using Toyota's 10W-30 oil which has the latest oil specification of SN Plus for both my 1987 Truck and my brother's 1990 Corolla and haven't had any issues with this oil so far.

From what I read, the ZDDP (Zinc) content is by far the most important for engine break-in (which you are doing), but is less important after the initial break-in.

I do agree that you really shouldn't mix a modern oil and a separate ZDDP additive, as the oil chemistries my not be a good match. A lot of people here do use the Shell Rotella for the extra Zinc content without having to worry about extra additives.