Guide bush and pin on front brake calipers

[kiddfrost]

I'm going to be fitting some s3 hubs soon so am going to be taking that area apart. While I'm at it I was going to replace the guide pins and bushes on the calipers. Can someone tell me if you are meant to grease the bushes and pins? I'm not sure as the bush seems to be made out of a plastic/rubber material.
Thanks