You probably don't need any lubricant for an exceptionally long time.
Some of us old-timers where pretty grumpy when bicycles switched to sealed bearings. They aren't perfect (more rolling resistance), they don't last forever, but they do last (stay greased and unfouled) a hell of a long time and require less skill to replace.
I have fantasies about building small drone submarines and releasing them in the ocean. Those I don't know how they'd sustain themselves. A little ground rover that has panels on it sounds more realistic. And yeah the life span I don't know how long they would last for.
But on a farm or homestead I would like to have little solar-powered wheel-driven drones pretty much that run around and do their own thing.
It would be neat though, have a sat module on the drone submarine, and then the sub surfaces at night. I think at my local lake is more realistic. Of course in reality these things would operate in supervision/not break laws. But I saw an intriguing video [1] before and I don't know... it's personification I guess.
Yeah I saw that recently I think it's cool. The wheel design is interesting, I don't know how effective that little weed whacker it has is. I was also surprised how small the panels seem.
edit: I follow this one guy on YouTube he built this thing [1], that's the basic idea. It doesn't really have a purpose, but it's cool.
In the long run though, imagine you're gone(passed on) and you built some robot that's out there still doing its thing. Probably talking RTG/space more like, than something on Earth that erodes.
