Tri-Flow is an excellent light oil. It has some qualities that regular sewing machine oil doesn't seem to have.
It penetrates better and doesn't gum up.
I've used many oils in my life, and I can tell the difference between regular oil and Tri-Flow when I lube up a machine.
That is why I recommend it.
You can get it at Sew-Classic. On the Tri-Flow pages there is a lot of information about it.
Joe