<VV> How MUCH Phosphorus and Zinc?

[Eric S. Eberhard]

Figures it would be that complicated!  And from my reading, lack of 
zinc is what causes the rounded cam problems.  I had two engines go 
flat on the cam lobes in less then 8000 miles.  Both were broken in 
the "traditional way" using 30 wgt dino oil of the mechanic's 
choice.  When I tore them apart and put a new cam in, and on a third 
engine I rebuilt thankfully once, I broke them in with the Mobil 
1.  It says on their site it is safe for break in.  I put 30k on one, 
25k on the 2nd, and 10k on the third -- no flat cams!  Still driving 
them.   It is a pretty precise test as the cams (except 1) were 
identical Clark's cams, the mechanic was the same, the cars the 
same.  I decided to do this the 2nd time around because of Web 
research that indicated that a zinc shortage caused this problem.  I 
believe it helps the oil film-up on the parts.  Oil seems to be a 
very personal thing, everyone has their favorite with good reasons 
all!  I probably would try some of the others if I could just buy it 
at Walmart and be done with it.

http://www.hotrod.com/techarticles/engine/flat_tappet_cam_tech/index.html

Note that the Mobil 1 separates the ppm for zinc and phosphorous ... 
and it is not the percentage this article says is usual.

http://phscollectorcarworld.blogspot.com/2009/03/new-engine-oils-for-flat-tappet-cam.html
http://www.carzwy.com/Why-use-a-high-Zinc-Oil-with-a-flat-tappet-motor-.html



E








At 02:42 PM 3/18/2010, BobHelt at aol.com wrote:
>In a message dated 3/18/2010 1:35:04 P.M. US Mountain Standard Time, 
>flash at vicsmba.com writes:
>in fact, if an oil lists
>1200 ZDDP how much Phosphorous and how much Zinc is that?),
>
>Hi Flash,
>The specification requirement is ONLY for phosphorous. It is 
>supplied by ZDDP which also happens to have some zinc. But zinc is 
>not a specified requirement.
>
>The requirement for GF-4 oils is a minimum amount of phos to be 
>0.06% and a max of 0.08%. These two numbers translate to 600 ppm min 
>and 800 ppm max. SM rated oils can have "any amount of phos but 
>usually the max is 800 ppm.
>Regards,
>Bob Helt


Eric S. Eberhard
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