Q. How many times can I pay just the interest on my car loan, instead of the full amount?

A. If you're in financial trouble, you need to speak to your lender before sending a partial payment of any kind. Auto loans don't give you the option to turn them into interest-only loans without permission.

If borrowers have compelling reasons for why they can't pay, lenders usually will offer loan extensions that allow them to pay just the interest for a single month and make up for that with an additional payment at the end of the loan.

The number of times you can miss a full payment will be very clear. Ford Credit, for example, often offers such relief to customers in areas that have been hit by hurricanes, according to Meredith Libbey, a spokeswoman for the wholly owned subsidiary of Ford Motor Co.

Customers coping with a death in the family or an unexpected medical expense, or those waiting for an insurance or income tax refund, also may qualify, Libbey says.

If you don't pay the full amount without your lender's approval, you'll be in default and your credit score will drop 100 points.

Make two or three unauthorized partial payments and your car -- which is collateral for the loan -- will be repossessed.

"We would much rather work with you than have the vehicle back on our doorstep. That is true with most lenders," Libbey says. "However, if you're not paying as agreed ... and then say, 'Let's work something out,' it's hard, because you're already behind."