I don't mean to be disrespectful, but almost everyone seems to treat their lawnmower as a second class citizen by putting on cheap parts and cheap oil. These machines have a sharp blade wizzing around at a couple thousand RPM right near your feet. I always use quality parts on my mower. Get the name brand bearings.
After having a deck bearing failure the 2nd. time and having to buy a whole new unit, I replaced all the bearings with good quality Japan made bearings (6x) and never had a failure ever the next 10 yrs./to retirement.