I have zero experience with your request, but will start out the thread anyway! I would imagine that bicycle and/or motorcycle people will have good advice.
If that were my problem, I would figure out a way to clean the chain first. Either remove it or concoct a way to clean it as mounted. A bath in mineral spirits or WD 40 should do the trick. You probably should clean the chain annually or as needed.
Then, choose your chain lube of choice. I probably would avoid a graphite lube due to how dirty they are (black residue).
This one might work - water insoluble, goes on thin to penetrate, then thickens up, anti-fling: https://www.datocms-assets.com/10845/1562019086-specialistrollerchaintds.pdf
I'm interested on what others will recommend.