My 5th gear is out so I'm driving it in 4th. Would or could that cause transmission problems 2006 mercury milian
It would only cause issues if any parts or fragments of the 5th gear or its mechanism etc were excessivly worn or damaged, and left floating around inside the gearbox. If there is just an external linkage issue, it will likely only be an inconvenience for you, however an external linkage issue is also quite easy to repair. Either way it would be an idea to have it checked out.