Bulk Oil Overage Reconciliation.

I want to know how every one handles the bulk oil overage or shortages, but mostly overage.
Some one had suggested that at the end of the month if I have more oil on hand than what accounting says I have, I should create a credit memo invoice to the parts department for the difference so that the parts department gets the gross profit for it. I just dont know how to do this. If I create a parts counter credit invoice to the parts department as the customer,wont that say that I am putting that back into inventory,thereby creating a shortage ? I really need the specifics of how to do this. Thanks
Some one had suggested that at the end of the month if I have more oil on hand than what accounting says I have, I should create a credit memo invoice to the parts department for the difference so that the parts department gets the gross profit for it. I just dont know how to do this. If I create a parts counter credit invoice to the parts department as the customer,wont that say that I am putting that back into inventory,thereby creating a shortage ? I really need the specifics of how to do this. Thanks