Rear axel seals

[RLDSL]

you have committed the #1 mistake on installing National or CR seals. Do not do this.
These seals are designed to be installed dry. hub, seal, and spindle area where it's installed is to be clean, dry and oil-free.
Why? the seal is designed to "bond" to the hub and spindle surfaces where it's press onto. The seal actually is a two part seal that rotates in itself. it is completely unlike a regular wheel seal where to lip rides on the spindle.
there's even a "proper" tool to install CR seals. National comes with a disposable installer for theirs.

There are also the new hand press type that do not require any tool to install, but both type still require an act of congress to remove once they have locked to the hub and spindle. It rather surprized me the first time I went to remove one of the hand press seals, I thought it would be an easy removal, turned out harder than any of the others. Once those things seat, they like to stay that way.