It's very nice that you spend some decent time with your grandfather. It is very good for him to feel remembered and cared for but also good for you as well. He is your link to the past. There will come a time when you would love to be able to share his insights.
By the time that I was 9 I had no more grandparents.I still remember my mothers mother and my fathers father. He was born in 1877! He was a grown man when he saw his first car and lived long enough to see the beginning of the space program. How I would love to have a conversation with him now!