Well it is time to get my AC recharged,  it is still blowing cool air but
it is not cool enough.  I called the dealer today and I had a few
questions.

1.  My 91 uses R12 do I have to replace it with R12
2. If the above is true how much should the system need and approximate
cost
3. The service manager said it is not necessary to add oil to the system if
the freon has NOT been completely discharged.  Is this true?
4. I the system needs to be re-lubricated is there any significant cost
added to the labor/parts?
5. How do you tell if there is enough oil in the system to maintain the
its' integrity.

Thanks is advance,
Dan