Kath wrote:
replying to Ron, Kath wrote:
I bought a quart of SAE 10W-30 at Ace Hardware. It is their brand
motor oil
for all seasons. They told me it is non-detergent. I ran it in my fans
all
summer with no problem. I hope this is OK Im starting to second-guess
myself

I don't think a fan runs as "dirty" as a car, so I think you'll be
fine. The idea of the detergent is to remove sludge, I think. Of
course, I don't have a fan that you have to add oil to. Anyway, don't
lose any sleep over it.