You could be using too much. I limit oil (castor) to a single 1/8" wide drop mixed with a few sprays of Devacurl Set it Free
in palms. I then press/scrunch my hair with palms after hair is styled but still wet. This leaves an extremely thin film on the surface which keeps hair soft and moist when dry. I don't use oils otherwise except an occasional overnight treatment which gets washed out.
Two products I recently added to my line up are great at keeping my hair moisturized: SheaMoisture Shea Butter Leave-in, and Afro Detangler.
The SM leave-in I blend with aloe vera gel (it's pretty thick) and rake in wet hair as a leave-in. you can use with or without gel. The Afro Detangler is fabulous for detangling dry hair and spot curling (it encourages curls and twists). When dry it sinks right into the hair and is non-greasy (I have no idea where those butters/oils go). It sucks on my wet hair as it breaks up the curl. I have folders in my Fotki (www below) that show both these products on my hair. I can't say enough about both of these products. I only shampoo maybe 2 x a month; they easily wash out with a co-wash.
SM Leave-in ingredients
Shea Butter, Deionized Water, Herbal Complex, Panthenol, Centrimonium Chloride, Glycerin, Cocoa Butter, Aloe Butter, Jojoba OIl, Vitamin E.(despite the oils, this is a non-oily product)
Afro Detangler: water,avocado/mango/shea butter, vitamin E, avocado oil, almond oil, wheat germ oil, lecithin, green tea, germaben II, mild fragrance.
Okay, now that I've raved about my favorite products, here are some oil-free products that also help keep my hair moisturized -- Robert Craig Conditioner, John Masters Citrus & Neroli conditioner, Blended Beauty Cleasing Conditioning cream (it's a no-poo).