On most cars the scale will be to me about a 2. I own a 77 Impala. It takes me about 20 minutes. Some transverse engines may be a little harder. If you do not have a repair manual it would be good to get one. These can give you step by step instructions for changing the thermostate and most other items on your car. Any Auto Zone or ORiellys have them. Do not forget to buy more antifreeze, you will lose some during the change out. Top off the radiator and overflow container as well.