Bearing and Rod lifespan
I'm a relatively new MK3s owner and I am curious how many print hours people are getting out of their stock rods and linear bearings.
My Oldest printer is about 6 years old, it has done a lot of printing and still has the original bearings and rods. but I lubricated the bearings during assembly and periodically cleaned the exposed rods and added a little lubricant since then
Get yourself a tube of Super Lube grease by loctite with PTFE.
It really is about the best money can buy for this job.
I use it at work, and for many maintenance tasks at home.
Third and second the above advice.
I've kept the rods and bearings as clean as reasonably possible (placing the printer in an enclosure really helps keep potentially harmful dust at bay). I've simply wiped down the rods using a soft dust-free cloth as necessary and sparingly lubed the rods a little every 4 months or so. As Clarmrrsn says, Super Lube PTFE is great for this job.
My MK3/MK3S rods and bearings have provided 3 years reliable service so far and I'm confident they'll provide many more.
Definitely lubricate your bearings. Not only does it keep them rolling smoothly, but it helps keep out humidity. I did not (it was not part of the current advice at the time), and mine have started rusting internally and will have to be replaced. Fortunately, it does not look like the smooth rods are damaged (they are the hardened steel variety), so I think I'll be fine just replacing the linear bearings unless I want to go with the premium Misumi bearings.