This forum is to discuss different features/issues of Oracle Financials modules ( GL - General Ledger, AP - Accounts Payable, AR - Accounts Receivable, FA - Fixed Assets & CM - Cash Management ).
According to my knowledge, there is no option of transferring from one book to other in fixed assets. You should retire it in one book and enter it in other book.
Add the asset in the new company "Y" with all details but in the Accumulated field enter the value after you calculate the asset Depreciation from the company "X".
For company "X", you can make retirement for this asset without any extra fees.