Here is part of a post I copied from this board a while ago. Can't remember who wrote it but I'm sure if you search for it you'll find the entire thread.
Winstrol does not convert to DHT although it is a DHT derivative, this is also the case with primobolan. To Finasteride or not to finastride? Well I mentioned above that Finasteride (Proscar) will only work to prevent the conversion of DHT by the 5AR enzyme. It wont do much to reduce hair loss on these because they are already a DHT derivitives. The hairloss is much to do with it stimulating the androgen receptors in the scalp.The best way to treat hair problems on these steroids are with Spironolactone or flutamide. Nizorol shampoo (or similar) is also good to some extent. Dont be fooled by either winstrol or primo. They can both be quite harsh on the hair.