I didn't know whether is was true or not because I'm not a diesel mechanic and don't pretend to be one. Considering a lot of people use conventional oil for the life of their tractors, It wasn't detrimental that I waited the 125 hours to make the switch regardless..
Your mechanic happens to be right , its better to run the same oil that came with your tractor until properly broken in ....yes some vehicles come from factory with synthetic oil but they are designed for this , moly rings and such ....would rather trust someone that actually works on the equipment than someone that can read a book......actually had an gravelly that I switched to synthetic oil before its first use rings didn't seat properly dealer advertised to switch back until engine breaks in ....oil consumption dropped from a pint per day to almost zero ...as the mechanic said it would eventually break in with synthetic it would just take longer with the cast rings.....