You can try conditioner-only washing. Nothing against the people who like Wen, but I personally feel it is too expensive (plus I don't feel some of the ingredients are appropriate, such as menthol) and you can get the same results from just using cheap conditioner from the grocery or drug store. Lots of people like Suave Coconut or Tresemme Naturals Radiant Volume Conditioner, but you can try other brands and flavors. What you want to look for is something without a lot of silicones in it. What you do is then wash with the conditioner. I wet my hair down and put it mostly on my scalp, rub it in really well, then pin my hair up in a clip, (I have really long hair)then finish everything in the shower, and then come back and rub my scalp again really well and make sure that all my hair has conditioner on it. Then I rinse, and put maybe 2 tsps. full from about my ears down as my ends are dry. I am blessed with an oily scalp but dry ends. :/ I'm lucky, I found a conditioner for $2 a liter that works well for me. I do use a lot of it to get my scalp saturated, but at that price I don't care. I can go 5-7 days between washings if I don't get horribly sweaty or into something where odors cling to my hair, like a smoke filled party.
The idea is that the oil cuts through the oil, but without stripping your scalp like soap does. There are several discussion groups out there on this subject. You can google conditioner only washing or CO washing if you want to learn more.
CeeCee
P.S. The cheap conditioner that works for me is at the Army/Navy store in Canada, and it actually has some silicones in it. I also still do use shampoo about every 6-8 weeks, to remove build up from the silicones and styling products.