Hey Deena4HapCar to keep the work-work simple, we've actually made items on invoices really flexible so that they work for both products and services.
You can name and describe each Item as needed in the Description.
We also included an optional Unit type to allow for multiple-item buys (like hours, or products) - but you don't have to use it if not needed for your business.
You can also save a basic Item Description (like "oil change") in your saved items, and then add that to your invoice and edit to add more detail for this specific customer (e.g. with "Castrol Edge 5w30").
And lastly, Invoices have the Notes to customer field, where you can add any general information about the work (like the make, model and rego of the customer's car).
But if that setup doesn't quite work for you, we'd love to hear what would be helpful.