They stopped doing a lot of stuff that made pumps last 50-70 years like that. How could they make any money if every pump lasted that long? In 50 years they expect you to replace that pump a half dozen times. Several motor companies used mineral oil in submersible motors. They also had double ball thrust bearings and another ball bearing for radial stability. With a really good mechanical seal they would hold that oil for generations. If the seal did happen to break, it was just mineral oil. It might make you more regular but won't hurt anything. I have a rebuilt 1962 Reda pump that I keep just to show how pumps used to be built.
Now there are very few motor manufacturers as the big ones bought up the little ones. When they got control they shortened the motors, changed from oil lub to water, started using plastic instead of brass for impellers, and put out recommended tank sizing charts that cause pumps to cycle themselves to death on and average of 7 years.
They were not counting on the Cycle Stop Valve coming along and making the cheaply built pumps last many times longer than planned. They do everything they can to discredit the CSV as it is considered a "disruptive" product because it makes pumps last so much longer.
