The transmission is automatic and it has 37,000 miles on it.

Change transmission fluid (and filter if applicable) every 40,000 miles.  You are almost due.  Use OEM fluid only.   Also, change differential and transfer case fluids at the same time so you get them all knocked out around the same time.

I know that you’ve mentioned in previous videos that GDI engines can cause carbon build-up over time

Those engines have both port and direct injection so you don’t have to worry about carbon buildup.   

so what can I do to make sure that this truck is on the road for a long time? I’m religious about full synthetic oil changes every 5k miles, but are there any additives or other things I should routinely be using/checking?

Continue changing engine oil (and filter) every 5,000 miles with full synthetic.   For all else, follow your owners manual.   Don’t waste your money on additives - just stay on top of the maintenance mentioned above.

1. Thanks for the info - I was definitely planning on sticking to 5k full synthetic oil changes, and great to know about the injection system and how it self-cleans. The only thing I’m questioning is the transmission service interval; all the resources I’ve seen have recommended transmission fluid replacement at 6 years or 60k, but checking the level every 10k miles or if the transmission is slipping or making noise. My truck is 2wd so I don’t think transfer case applies to me, but good to know about differential fluid as well.