Synthetic in Rebuilt Motor

[MOPARJ]

I now have 1800-1900 miles on my rebuilt 318 in my duster with all new seals, moly rings, everyhting and XE comp cam. Is it too early to switch to synthetic or should I do it while the seals are still nice and tight? Can synthetic be mixed with Hughes zinc oil additive?

 

[jaxle]

2000 mile as far as i know. its so the metal in the engine is saturated with real oil as far as i understand. as for the zinc; best answer is always the source, ask hughes.