Classic/Antique Car Repair: undercoating, surface rust, steam cleaning

Question
My boyfriend just recently purchased a 1987 monte carlo in excellent condition with 54,000 miles on it all original.  Unfortunaley he needs to drive it through this winter (although he would prefer not to).  We were just wondering if he were to get it undercoated for the winter, if it would de-value the car in anyway? Thank you for your time and advice

Jen and Marc

Answer
Undercoat treatment won't de-value a car (unless it's done badly).
However, if the current undercoat is still there, a good steam
cleaning after a snow storm will remove any road salt from the
under carriage. However, if the under carriage shows signs of
surface rust, please have it treated.