what oil is safe?

as of janurary 2007 desiel fuels and oils have changed,, goverment mandated to lower sulfur in desiel fuel,,like they have years ago in other countries,, the zinc in the diesel oil effects the partitulate matter in the exhaust,, so all desiel oil even shell rotella T has lowered theree zinc ( zddp ) content in diesel oil,,,,, the zinc in auto oil for muscle car and racing is still a matter no one really knows the truth,, since syntheic oils im told will find or make a engine more pron to leak oil,,, ?? ( any one having this problem ) ?? i am going to use what i have all along sae 30 wt, and use comp cams additive,, i recently broke in a set of lifters in an early hemi in my street rod with normal oil and comp cams additive,,,seems to work fine,, i get the additive at my local speed shop,,across the street from my house,,