This is the castor oil that I use: https://www.amazon.com/dp/B0734849YK/ref=cm_sw_r_cp_api_glt_fabc_dlT1_NN65YH46FKNEQEG5FV25?_encoding=UTF8&psc=1 Yes, I apply it all over my scalp. It’s not too difficult to wash off. I shampoo twice to wash it off. Shampoos and conditioner brands I use are Olaplex, Bumble and Bumble, Prose, and In Common ... Yes, I use them all lol I like to switch it up with every wash. Hopefully I answered all your questions 😉
I got one from amazon that doesn’t smell at all. Has absolutely no scent:
100% Pure Castor Oil - Huge 16 OZ... https://www.amazon.com/dp/B0734849YK?ref=ppx_pop_mob_ap_share
Hope it helps!