Using WF to auto-assign a value to a Service Request

I have workflow setup to automatically assign the Owner and to pull in the Product Description and Category to new Service Requests.  This is working great except when the user has a role that has Create/View access only to Service request.  When that occures we get a message like the following: "Operation Failed: Edit. Record Type: Service Request. Access Level: Read/Create (SBL-DAT-00284)..."

We don't want our Customer Service team having access to change the service request once they are entered but want to use WF to set the initial values for these fields afteer the request is entered.  Does anyone know of a way to have WF use the admin or some other role to assign values?