Generally people say to change it at 25% oil life.
I don't know how accurate those fancy timers really are. I feel like they are are just for people that don't pay attention and need something to remind them that someone major is going to brake if they don't do something.
Can send your oil out to
Blackstone Laboratories for a few oil changes and determine if you need to change it sooner or later, or just do what you want. Oil changes are relativity cheap compared to other work needing to be done on trucks imo. I go 5-7.5k miles and change it and always use full syn. Can do a 7qt oil change for $40 myself (including the filter). I have enough oil in my basement for around 6 changes as I stock up from BJs when oil goes to around $4.16 a quart for Mobile 1 (single containers in 6 packs).
Here's another TSB for 2012-2013
09-001-12 FIAT Technical Service Bulletin
www.tsbsearch.com
The acceptable loss is the same except for after 50k miles it says it's normal to lose 1 quart of oil every 750 miles driven. Could you image owning something with 50k miles burning through a quart of oil every 750 miles?