2N hydraulic cylinder scored

That theory about changing the oil in the N lift previnting the scoring of the cylinder is not exactly right.The real problem with the N hydraulic system is that there is no filter for the oil and that the oil is picked up too close to the bottom of the reservoir and the junk that comes into the system through the seals on the rocker shaft and the stuff that us shed off the unlubricated parts of the linkage and the pump and the pto etc just goes around and around in the system untill it finally finds a cozy spot to stay.
Changing the oil does not get rid of all the junk that is in the bottom of the lift. The only way to get rid of it is to remove the pump and pressure wash it or put it in a parts cleaner etc. The rubber rings will not score the clyinder walls like the steel ones will when a foriegn particle comes between the ring and the cylinder wall. It will begin to cut the rubber ring down and eventually it will leak just like the steel ring did but the cylinder walls will not be nearly as scored.