If we had ZDDP numbers for JGDT40,would we know if it is good/bad ? Tribology is a tough enough subject to master but when you overlay the M96 quirks on the subject it becomes fiendishly complicated to figure out which is best oil based on any data.
It comes down to faith in whoever makes a recommendation. So it is a 1990's Mobil spec that is no longer available vs.JGDT40 Lake Speed/Raby.
This link gives some
comparative data for Mobil 1 vs. JGDT40.Just scroll down to the piece on oil.
Flat 6 Innovations Summer Newsletter