Motor oil

[tirebird]

Norm, you're right about most of the Mobil 1 blends but the 15w50 Mobil 1 still has the old formula containing the higher(than today's) levels of zinc and phosphorus. Here's the information from Mobil 1's Product Data Sheet.
"Mobil 1 Extended Performance 15W-50 is formulated to provide outstanding engine protection for high performance engines and for consumers who want a higher viscosity oil and higher anti-wear performance ( ZDDP) than typically required by modern vehicles."