Helping grandparent avoid scams

My grandad enjoys going online and it’s an important way for him to maintain a social life. But it does mean he is exposed to loads of scams, which he is completely unable to identify. He regularly asks us to help him claim the car finance money he’s owed back, despite having never bought a car on finance. Etc etc.

How can I speak to him about this in a sensitive way that can help him to understand the risks?