The best thing I've found for washing wool is Eucalan. You don't rinse it out, it contains lanolin for re-oiling the wool. Turn your machine to the rinse part of the delicate cycle, put in the Eucalan and your items, turn it on. Also works well on other animal fibers like angora and cashmere.
Although you don't notice an odor, it's probably not a great idea to go too long between washings. The salt from sweat will eventually eat through the fibers. Personally, I can't wear any kind of animal fiber next to my skin without wanting to scratch myself to pieces, so for me the synthetics are the best thing since sliced bread. They don't collect odor as I wash them soon after every use.