increased friction. No matter how well you care for your longer hair, the acts of washing, drying, brushing, straightening, curling, dying, and other things will damage it, let alone things like getting longer hair caught in doors, laptops, and Dremels! (Having said this, I've always found the greasy roots, dry ends products never seem to do a good job of either!)
Don't try to solve this problem with your shampoo: This is a job for your conditioner. For your shampoo, concentrate on those things that will clean your hair and remove the sebum. Choose surfactants that will remove grease, like C14-16 olefin sulfonate, DLS mild, and so on. You don't really need to do much washing of anything below your shoulders because the goal is to remove the grease. If you're rinsing and repeating, wash the length of your hair to get rid of any environmental pollution and styling products, but only do it the once and very lightly.
Choose a good conditioner (click here and scroll down for recipes). You can go with something more oily for the ends, but keep it away from your scalp, because what's the point of getting all the oil out only to put it back? (During the colder times of the year, my husband and I often use my conditioner bar for the above shoulder hair and a more intense conditioner for the below shoulder hair as we don't want the oils we put in our liquid conditioner on our scalps.) And load your conditioner and leave in products with things that will reduce friction - silicones, silicone substitutes, oils, and so on - don't brush it so much, and definitely don't do the towel drying violently!