I have spoken with a credit union lender, the explanation I recieved on this issue is that the application used is a "loan liner" and it covers all notes extended. that way you can have a co-signor on an app that covers all loans requested. Now, a co-X would have to sign the note each time but the app is covered. A closed end car loan or note would require the co-X responsible on that one particular note only, just in case they would want other credit extended. This does not however exempt them from typing "renewals" for an advance on my car loan if I needed $1,000 for something and I had the equity. In this instance open end, I think, mainly covers the application process and any co-Xers. If it makes sense to think of open end and closed end to refer more to the application than the actual note itself. I can't really think of an advantage to this off-hand, except if you had a credit that went bad and you could hook the co-Xer on any additional, not related credits. This is my opinion from a conversation I had with a loan officer at a credit union, I can't guarentee my interpretation is perfect or correct.