Doug White wrote:

I have such an oiler, and put "RemOil" gun oil in it. The oil is so thin
it leaked out of the oiler in short order. The one I have is aluminum,
with a push button that runs a little plug at the end of the oil tube. I
have another one, but I haven't tried it. I don't know if the first one
was defective, or the design/manufacturing is poor.

I like Microil a lot.

http://www.kanolabs.com/

Bought a quart a few months ago, which should
last me several lifetimes and got a free can
of Aerokroil, a most excellent penetrating oil.

Good company and good products.