Cores must be returned in a rebuildable condition.  It must be returned in its original packaging.  You must follow the packaging instructions that come with the rebuilt part. Do not ship a core that leaks oil, this will cause you extra shipping expense. UPS will return it back to you for repacking at your expense. The returned core part must apply to the same parts application.  You will receive an EMAIL core return and follow the instructions. You must return the core within 15 days of receiving it. Core credit requires the builder of the part a chance to examine the core.  This can sometimes take up to 30 days.  Therefore, core returns can take up to 30 days before you can receive your core credit.  When your core has been approved, we will credit your credit card number.