Hi Karan,
Rest assured that if the bottle of alli you purchased was in date you are getting 100% potency from it.
Not everyone experiences or sees the oily discharge when taking alli.
It is dependent on a number of factors:
1) The amount of fat consumed.
2) The food you are eating, the more fiber the less noticeable the oil.
3) Your body
As you see a gradual weight loss you will be assured that alli and you are doing the job.
Hope this helps.
Sopha De Monte RPh