Is it ok using baby oil after 4 months of hair transplant ?

There should be no issue with baby oil itself but you should have a good reason as most people don't rub baby oil on their scalp. It is always a good idea to follow up with your doctor for a recheck if you have concerns.

It is okay to use baby oil after 4 months of hair transplant but I am concerned that it may cause more problems than offer any significant benefit. Using too much baby oil after hair transplant might result in future hair loss, dandruff, eczema, and likes. I suggest that you take care of your hair like you were doing before the surgery, use mild shampoos to get rid of flakes and odors that might inhibit proper hair growth.

It should be fine to use baby oil 4 months after hair transplantation, but it might increase the risk of dandruff. You should speak with your hair transplant surgeon about the specifics, but I am not sure that there is much benefit in using baby oil in your hair.

You don't need to use baby oil at 4 months mark after a hair transplant.  However, it is harmless and at this point you can treat your scalp as you used to before your hair transplant.

It is safe to apply baby oil to your scalp four months after your hair transplant.  I would only caution that the scalp has abundant sebaceous oil glands already and does not usually need extra oil except in rare cases of eczema and psoriasis.  In fact, dandruff/flaky scalp is believed by dermatologists to be partly caused by inflammation resulting from excess oil and yeast overgrowth.  Lack of adequate cleansing or washing with shampoo can result in excess scalp oil and consequent dandruff.  It is best to control scalp flaking with a dandruff shampoo which will control the excess oil and yeast.