FYI... JD Plus 50 is "dumbed down" Delo or Delvac. You'd be better served running the real deal (Delo or Delvac). JD plus 50 is manufactured for John Deere by Chevron (West of the Rockies) and by Exxon/Mobil (East of the Rockies) to a very specific ad-pack which is not as stout as Delo or Delvac.
This info came straight from a JD Master Mechanic.
Believe me or not, it doesn't matter because it's working for you which is great.
Rob
Thats exactly why I pulled up the manufacturers info myself, to dispel the rhetoric. There is no way Deere is going to extend OCI's on its own equipment upto 500 hrs. with a "sub-par" lube.
Just looking at the UOAs, the Plus 50 has a more robust add pack than delo or delvac dinos.
I believe that you are correct in reporting what the mechanic told you, but I don't think the mechanic's information is correct based on observed data.