rats and guinea pig

Question
I Have 4 rats and a 1 guinea pig we had 2 guinea pigs but 1 died in feb and we have no plains on getting other. we introduced the piggie and rats together 1 at a time that way the no one got to stressed but it was just the opposite the rats like the piggie and are always trying to see the piggie and the piggie loves being around the rats so play time is 4 rats and 1 guinea pig. They not only play together but they spend time cleaning each other. My question is do you think the rats have accepted the piggie in to the group enough to place them in the same cage? well cages 2 xlarge and 1 large guinea pig cages. 1 xlarge and large cage hooked together for rats and the other xlarge cage for the guinea pig. It wont be all at once 2 or 3 hrs a day and after 1 of our rats dies she has a tumor and we replace her with 2 more. So it will be a while but I'm trying to get as much info as I can. Wont even be thinking about it if they didn't get along so well. thanks for any input.

Answer
What you will want to do is clean the cage and provide each rodent with their own home. Then place them in the cage together during a time you can observe their behavior. This is to insure that no one get territorial over space. However, with them getting along so well and even cleaning one another it would be logical that they would get along perfectly. Most rats get along with guinea pigs given proper introduction, as you have done. If they do not harm one another drawing blood or making injury then you should be just fine. Dont worry if there is a lot of squeaking and chasing at first and even some rearranging of homes, that is normal.