I recently spoke with a tech guy at Mobil1. He told me the ZDDP level in their 5W-30 was not enough for my flat tappet Windsor. He told me the ZDDP level in Mobil1 5W-30 was 800 PPM or less (thus the starburst).
I then bought a case of 5W-30
synthetic from another producer and dumped 9 quarts of it into my engine. I did this because their tech guy assured me that the ZDDP level in their product was around 1200 PPM ZDDP. I also took a sample of the new
oil and sent it out to be analyzed. When I get the results I will post them on this thread. Last year I sent a sample of the Mobil1 5W-30 and the ZDDP level came in under 800 PPM.
BTW, according to both the Mobil1 guy and the other guy it's not so much the
zinc but rather the phosphorous that prevents the wear.
Bob