I just purchased a 2001 honda civic ex a few days ago. I was told that the synchros were bad in the transmission . (Keep in mind I haven't had a chance to put it up on a lift and check it out yet, just trying to get some ideas to look for when I do). But the guy had told me that he has swapped 2 different transmissions into the car and within a week's time it does the same thing. The car will go into every gear and drive smooth and fine but will not stay in any gear, you have to hold it in each gear. I highly doubt that all the synchros would go out at the exact same time on 3 different transmissions, this is why I don't believe this is the problem. Just looking for some Input on ideas to check out. If anyone can throw some ideas out there to give me an idea of things to check out I'd greatly appreciate it.