It would be in your best interests to verify what type of oil. I'm glad Boosty brought it up.
On the rest:
Grab the pulley (with the belt off) and spin it back and forth just like the belt would. You'll 'feel' the slop and rattle (looseness) if your coupler is bad.
Now grab the pulley and pull UP like you're trying to lift the SC from the car, and down, and left and right to check for the bearings. It should be firm. I don't expect any wear on yours.