Use what the book says!!!!!
The newer engines have much tighter tolerances. On TJs and older you could get away with running thicker oils. Running even 5w-30 WILL blow out your seals and push your bearings past their usable limit. Do you want to do a minor rebuild of the engine? Then put in a heavier oil. Seriously. I work on generators for a local Caterpillar dealer. We end up rebuilding natural gas engine with only a couple hundred hours on them o CE or twice a year because of this exact issue. Someone running what the manufacturer recommends not to.
End rant.
If you're worried about your oil not making it to the next recommended change, get an oil sample kit, pull a sample at say 5-6k, and send it in. You'll have your answer on whether to Chang it or not within a week.