[6pack] ZDDP again

[Dave Russell]

If my calculations & the published information are correct --

One pint of the old GM EOS contains 0.71 % Zinc & Phosphorous by weight. 
Added to six quarts of oil, this comes out as 0.059% or 590 PPM increase.

One 1/4 pint container of ZDDPlus (Moss) contains about 6.36 % Zinc & 
Phosphorus by weight,  or 1.59% for one pint. Added to six quarts of 
oil, this comes out at 0.13% or 1300 PPM increase.

Assuming that the accepted ZDDP MINIMUM requirement to protect 
non-roller cams is 1200 PPM, & the existing oil has NO ZDDP,

Adding two pints of GM EOS would bring six quarts of oil which contains 
NO ZDDP up to 1180 PPM.

Adding 1/4 pint of ZDDPlus would bring six quarts of oil which contains 
NO ZDDP up to 1300 PPM.

If we believe some of the available published oil spec numbers (ever 
changing & conflicting) some oils still contain 800 PPM to 1200 PPM of 
ZDDP & would require less of either additive to make up the difference. 
Some brands such as Valvoline VR-1 still claim to contain 1200 PPM on 
certain oil grades.  See next paragraph.

Go here:    
http://www.api.org/certifications/engineoil/pubs/upload/1509_16thedition042007.pdf
To complicate the issue, if you look here near the end of the document, 
& read between the lines, it seems to indicate that certain 
grades/weights of SM rated oils such as 20W-50 are somewhat exempt from 
the reduced Phosphorous-Zinc  limitations. Only the "Energy Conserving" 
grades have the reduction.  I note however that the published 
acceptable  cam/lifter wear limits  on test engines would still be too 
high  for my comfort.

This may explain why some companies such as Valvoline continue to claim 
that their "SM" rated 20W-50 and the heavier straight grade oils still 
contain adequate ZDDP for older flat tappet cams. It does seem strange 
that only certain grades of "SM" rated oils would have reduced ZDDP 
content, but this may be the case.

I personally will continue to add ZDDP to any oil that has an SM rating. 
I don't think that there can be too much in the oil within reasonable 
limits. I would consider 2400 PPM as the upper limit.

Dave Russell



DLylis at aol.com wrote:

>I suppose I could call and ask for myself, but given I am basically lazy,  
>does anyone know what ppm results when you add the stuff Moss is now  selling?  
>They are saying to add 4 oz to 4 - 5 Qt oil sump.  What if  anything is the 
>downside of too much ZDDP?
> 
>David  Lylis
>69 TR6 CC26160L
>60 TR3A TS74461LO