I wanted to add this to the discussion on oils and ZDDP since is really relevant to that. Maybe the moderator can move it.----------
Many of you have read my paper on oils, specifically aimed at the selection for classic cars with flat tappets.
One of the thousands of readers sent me a sample of oil from the late 60's, so I had it analyzed and added the results to the report. The full (updated) report is here:
Selection of oil for flat tappet engines For those only interested in the synopsis, here goes:
After a 30 minute shake to get everything in solution (not that it hadn't gotten shaken a bit in the mail), the can was opened and 120 mm was sent out to my lab for analysis.
This sample can had MM-MS-DG stamped on the top of the can, which means, in the current API system it would have met SC standards of 1964 or their upgraded 1968 standards for SD (both called MS back then), and DG means a CA for diesel use. The use of the word "plus on the label might have signaled the higher level that became "SD".
Additives are strange.....
First because it uses 124 ppm of barium. That is a DEMULSIFIER that would try to separate water from the oil. Obviously discontinued as that would cause more rust and sludge. It is more often used in turbine oils to separate the water in the drain area of the tank.
The normal additives are:
Calcuim (detergent): 807 ppm (vs about 1800 top 2000 for an SN and 3000+ for a CI-4)
Phosphorous (part of anti-wear package with zinc): 482 ppm (vs a minimum of 600 ppm and maximum of 800 ppm for an SN oil today and about 1300 to 1400 in a CI-4 - limited to 1200 in a CJ-4)
Zinc (part of the anti-wear package with zinc): 517 ppm (anti-wear packages have about 10% more zinc than phosphorous in any formulation that uses ZDDP).
So this was a post-1964 oil (possibly post 1968). It has a little more than half of what today's SN oils have in anti-wear and detergent, or about a third or less of what a CI-4 oil has.
When GM offered their additive to raise the ZDDP levels to this level or so, I can see why. But cannot see the need to raise it higher than CI-4 with the aftermarket additives on the shelves.
