my hair is quite oily actually

i really wouldn't recommend that. maybe just go to the store and get some more shampoo....

Its okay but it is not the best and will probably dry out your hair after a while but if you need to thats fine. Just get real shampoo and conditioner when you can. Even if your hair is oily just get a shampoo for oiliy hair and that will probably be a bit better.

uhm not on a regular basis

it will dry out your hair and make your scalp oily

Well, as your probaby know shower gel ISN'T for cleaning your hair, it's for cleaning your body. It safes in terms of that if won't cause your hair to fall out, but I wouldn't advise you clean your hair with shower gel. Best thing to do is just wash it with warm water throughly until you get your shampoo (and conditioner!)

It'l work, but it will leave your hair feeling thik and almost sticky.... I did that once with Victoria's Secret shower gel. I didnt get the texture i wanted, but oh did it smell good!