What Oil Do You Use?

Just bought a 1982 XS400s and want to know what oil I should use. Ive heard 10w40 or 20w50. But I would like to know what brand you use and the name of the product. Thanks.

http://www.xs400.com/threads/xs400-oil.19252/#post-180108 Info on these threads. Welcome to the forum. Post some pics of the bike!! We love pics.