The compressor is fine blows cold its the clutch that is squeaking and its 10 years old so I decided to replace. When adding oil should I measure what comes out and fill new compressor to that level? The compressor calls for 6.4 oz. 

Look in this article in the "Repairing A/C System" section.

 

Made it easy for you...but you should still read what @IBMobilerecommended.

 

You will need to drain the oil out of the old compressor into the measuring cup and make note of the amount. Discard old oil.  Now, drain the oil out of the new compressor then add the amount, in fresh oil, that was drained from the old compressor plus 2oz for the new accumulator and 1oz for the new condenser to the new compressor.