I'm probably not the one you want to answer, but I just thought I would drop in because I have never "sealed" with oil. I just shea butter my hair from root to tip after washing and every other day after that until the next wash - which is usually 3-4 days later.
I have not had one split end. Breakage is a non issue now that we are back stateside.
Don't know if this is helpful, but I did want someone to know that there are butters that probably do just as good a job of sealing.
I am natural 4a/b.
HTH!!!
cj