I hope you don't feel the need to use the castor oil, it can actually dehydrate you pretty badly, which puts both you and your baby at risk. My friend's ob suggested it to her and she went to the pharmacy to buy some and while there asked a pharmacist about it inducing labour, and the pharmacist told her all it will do is give her dirreaha (sp?) and make her feel very sick and could possibly land her in hospital hooked up for fluids, worst case it could cause serious distress with the baby which could lead to a c-section. The pharmacist also told her it was irresponsible of her ob to suggest it, since in some cases it can be very dangerous.
I have another friend who took it because her dr told her to, and she said that she has never been so sick in her life. Violently ill for 2 days, barely left the bathroom. She started labour on her own several days later.
I'm just very suprised that it's still suggested. I would not recommend taking it. I'm sure there are others who would stand by using it, I just don't think it's worth it, personally.
I am sending happy birth vibes your way, good luck!