Hmm, could your problem be that you haven't put in the moisture to then "seal" it in?
If you're just putting greases and oils on dry hair, it most likely will not do anything for you except sit on top.
When you wash your hair, you need to then apply a leave-in conditioner (maybe creamy if your hair is really dry), then immediatley apply your oil or maybe a butter (I wouldn't recommend grease). The oil will seal in the moisture from the wash (water) and the leave-in conditioner.
Maybe for a while, you could keep your hair in a damp bun and spray it with a moisturizing mix throughout the day or twice a day. Make a mix with distilled water, conditioner, and oil...and maybe add an eo like rosemary to stimulate growth while you're at it.
For an oil, I highly recommend coconut oil but you could also use Proclaim 7 or Wonder 8 or any of those oil mixes. For butters, I really recommend shea butter though it might be too heavy for your relaxed hair.
I hope this helps! Throw out the grease!