What is a safe break in period for a new diesel before pulling a heavy #13000 + trailer?

 

Is there a break in? - yes
Are there a lot of differeing theories about it? - yes
Do you need to wait for it to complete in order to work it? - My viewpoint is No

Use your truck like you need to use it, just don't abuse it. This rule applies whether your truck is broken in or not. Breaking in can take up to 15k so if you intend to wait, so depending on how much you drive it can take a long time. Just remember to change your oil often. First at 3k, or sooner if you like, then regularly therafter and you should be just fine.

 

Make sure you warm it up maybe lay off those burnouts at the stoplights and you should be fine. Maybe put at 1k on it if you can to make sure the tranny gears and rings set up all nicely