Our whole-house fan is mounted in a gable wall near the roof peak.
I.e., not readily accessible and irregularly maintained. So, 50 years
after its installation and maybe 30-40 years after its last lube, one of
its bearings seized. It was one of the pillow block bearings holding
the fan shaft. It's a brass or bronze sleeve bearing with oil grooves
in it. The oil in there had been baked solid and immune to various
solvents and to a lye soak. It had to be chipped out with a pick.

Once cleaned out and reassembled, my first choice for its oil refill was
10W. It ran right through! OK - I tried 30W: it, to, ran out. So, the
bearings are either so worn that they aren't going to hold any oil, or
I'm using the wrong oil. They definitely do not seem worn - they slide
on readily, but without any noticeable play.

I'm inclined to try gear oil, but I thought I'd collect RCM thoughts on
it first.

Thanks,
Bob