It would be informational if we knew why Byrd needs this info. 3.5# is a half gal (aprox). That is a lot oil for a system for which the oil charge is usually measured in fluid OZs. Manuals do have mistakes in them once in awhile especially when translated to english by a foreign engineer. The R4 sounds reasonable for a critical charge type system. Refrigeration is not a good DIY endeavor; too many nuances and technical stuff like thermodynamics. Too much or too little of either refrigerant or oil can cause heat transfer problems or compressor failure.
Very little oil is lost through a leak. Compressor manufacturers provide info with with instructions to assure the proper oil charge is added during a change out. Those little compressors have no sight glass or test cock to check oil level. I always hated getting stuck with the bosses friends auto systems when I was a AC&R Tech as they were out of our industrial league.
Ron