Welcome winter, enjoy your vintage machines. They are fun to work and sew on. And they are truly workhorses for any project you could want to make.
Chance, if you have a manual. it will tell you what needles to use. My Singer 15-91 is electric and takes regular sewing needles. My treadle is a Singer 15-88 and it to uses regular needles. But there are some machines made at that time that used specific styles of needles. That all I can say to help you.