Hi Hessam, I don't think the thread was saying that the elevated zinc in HDEO causes more wear. My take home was that the high zinc in a HDEO might not be as active as the zinc in a PCMO, so the "effective " zinc might just not be as high as we think by just looking at the zinc ppm concentration.
However after reading this, I am much less worried about zinc levels in oil.
http://www.penriteoil.com.au/tech_pdfs/0Zinc Myths & Legends Nov 2014.pdf
It seems the high zinc levels of the past first weren't often as high as we think, and second the zinc was elevated because of the lead (Pb as TEL) in the petrol reduced the effectiveness of the ZDDP, so it's concentration had to be increased. With lead free petrol today, less zinc (ZDDP) is required.
Another thing I learnt from reading the Penrite web site, is that Boron can be used to do the job of Zinc. Plus there are other things like Titanium and Moly that do similar jobs.
So an oil with "only" 800ppm Zinc, but also lots of Moly and Boron, being used with lead free petrol, is probably as good, if not better than a high zinc (only) oil from the old days being used with leaded petrol.
And dont forget, if a HDEO oil is dual rated (eg API SL) then it was developed to be safe and effective in petrol cars.