I picked up the April edition of UK Cosmopolitan and they have a Q&A section where this was in:
Q: My friend conditions her hair with oil and it looks amazing. So why does mine go lank when I try it?
Now, if it was me being asked that, I would start explaining about different hair types and penetrability of different kinds of oils
Instead, this is the answer given:
A: You can use olive oil as a deep conditioner (Leave on for an hour or so) but you must wash it out thoroughly. Alternatively, some light plant oils can be worked through the hair before blow drying for glossy, silky strands- but use only a few drops. Try beautiful-smelling Orofluido hair oil, £ 25Could this answer be any less of a help?!