entering mileage

I am using the Online Version, and want to manually enter the mileage expense for each job that the company has.  I am having to use Excel to make a spreadsheet to keep track of the mileage per job because online doesn't offer that option.  I will not be billing the customer for the mileage, but want to track this expense along with the others.  Would the correct thing to do be use a journal entry with a credit in the COGS and debit in Auto and Truck Expense?