How do I change my racist grandpa's point of view?

To be honest, I havenít seen my grandpa since I was a child after we moved away to a different state. After my parents retired this year, they decided to move the whole family back to New Jersey to be with our relatives. I noticed the region has changed a lot since I was a kid, especially with all the new businesses and also a booming population of Peruvian Americans. Well, I took my grandpa out for lunch yesterday at his favorite diner and to my horror, he made really offensive racist comments towards the Lima women who were working at the establishment.

I felt so ashamed sitting down next to him, especially because I was never raised by my parents to discriminate people by the color of their skin. I donít want my grandpa to continue having this kind of point of view towards POC. How do I change his thoughts on the matter without seeming like Iím imposing my own beliefs? He is still my elder and I respect him, even though what he did yesterday was really insulting and off-putting.