How is the ZDDP number calculated for oils? For example, simply because there is a chart readily available... From the Mobil 1 FAQs:
Both have ZDDP levels of 1,000PPM. Onto their handy chart... Mobil 1 0W40 has 1,000PPM of phosphorus and 1,100PPM of zinc. Mobil 1 High Mileage 10W40 has 900PPM of phosphorus and 1,000PPM of zinc. What am I missing?
Mobil 1 0W-40 already contains a higher level of ZDDP (1000 ppm) that could benefit your flat tappet engine. We also have a Mobil 1 High Mileage 10W-40 (1000 ppm); see our table listing the phosphorous levels for all Mobil 1 motor oils.