Was told theyre suppose to stay dry inside (around the bushing) is that true? Mine has brake fluid all inside and was told to replace ASAP.

I always thought these cylinders rarely ever need replacing. What causes them to leak? Is there any way to prevent it in the future?

 

Judging from all your posts you dont have a reliable car. There might be a rebuild kit available. If you posted pictures you could get mote accurate help.