My cat is acting normal otherwise, but has this odd red wound it looks like a scrape. he does go outside sometimes but I am keeping him until he heals. Do you think if he isn't ill otherwise this is best course of action? I dont' think there is infection to need antibiotics

Hmmm....I tend to always say this, but is it possible that it is ringworm? If he goes outside, it could be any of a million things. I suggest that you take your kitty to the vet to have him/her take a look. :)

How long has he had it for?

Sounds like ringworm (that's not necessarily "round") - especially if the cat goes outside. Make an appointment with the vet. Ringworm is contagious - even to people.