Another good read from the compressor works web site. They claim there R4s are new and are built to last. I may call tech support and verify the built to last processes they claim on the web site. (autozone sells these for $238 new).
http://www.compressorworks.com/default.aspx?page=Rfour
"Best Practices
Have the system refrigerant recovered by a certified repair facility.
Always replace the orifice tube, accumulator, and receiver/drier/filter when replacing the compressor.
Ensure that the correct amount and type of A/C lubricant is used. OE suppliers recommend the use of PAG lubricants.
Add approximately 25-30% of the entire system lubrication charge to the compressor. For example, a GM system requiring 8 ounces of PAG lubricant will have approximately 2.5 to 3 ounces of lubricant added to the compressor. Whenever possible, add the lubricant in to the suction port of the compressor as opposed to the discharge port. The remaining 5.5 to 6 ounces of lubricant should be added to the accumulator (or to the evaporator if the system has a thermal expansion valve). One ounce may be added to the receiver/drier/filter if desired. The lubrication specifications are normally expressed as the lubrication requirements for the entire system. If the entire system is not flushed, it is almost impossible to determine the correct lubrication refill requirements.
Turn the compressor shaft a minimum of 12 turns as part of the installation process. This will aid in the distribution of lubricant throughout the compressor. Please note that many compressors are very difficult to turn by hand. When turning the GM R4, HR6, HD6, & HT6 compressors, a spanner wrench should be used.
If the system is heavily contaminated, it may be necessary to replace additional components to ensure that the compressor will function as desired.
If 'Black Death' symptoms are present (a dark gray or black oil/oily residue), it may be necessary to replace the entire A/C system. Failure to do this will result in repeated compressor failures.
Flush the entire system with an approved flush chemical. Some chemicals may cause serious harm to A/C components. Brake Clean, Acetone, Mineral Spirits, and Gasoline are examples of chemicals that should never be used to flush an A/C system.
If adding dye or another leak detection chemical to the system, ensure that the correct type is used. No more than 1/4 ounce of leak detection dye is necessary. If using refrigerant with dye, the additional dyes are necessary. Excessive amounts of dye may cause a break down of system lubricants.
Shaft seal leakage or seepage is normal for the first 8-10 hours of compressor operation.
Ensure that the air gap (clutch gap) is within specifications. When testing the gap, a brass or plastic feeler gauge is suggested as metal gauges often give erroneous readings.
Always 'burnish' the clutch as part of any new compressor or clutch installation. This can be performed by using the low pressure switch to manually cycle the compressor on and off 30-40 cycles. This procedure should be performed only under normal engine operating temperatures and when the engine is at idle speed. This procedure will aid in reducing or eliminating clutch slippage and possible clutch failure.
When recharging, ensure that the correct refrigerant type is being used for the system being serviced. If retro fitting (migrating from R12 to HCFC134a) is being done as part of the repair, be sure to follow the specific manufacturer's instructions for this procedure.
Lubricate all O-Rings with mineral grade lubricant.
Evacuate (pulling a vacuum) for at least 30 minutes. Failure to properly evacuate the system may result in a failed compressor or result in a system that fails to cool properly.
Recharge to OE specifications. If possible, have the system service by a certified and licensed technician. It is almost impossible to properly charge a system using pressure as the only measurement.
Test the system for proper performance after the repair to proactively diagnose possible problem areas.
Test for leaks after repairs have been completed.
Replace the fan clutch (if applicable) if the vehicle has more than 50,000 miles or if the system displays excessively high high side pressures.
Late model HCFC134a systems may require the replacement of the condenser as part of the compressor or A/C system repair. The design features of these condensers prohibit the ability to adequately flush (clean) the condenser. Failure to replace the condenser may cause compressor failure or inadequate cooling performance".
Interesting on the "burnishing the clutch"; cycle 30-40 times. Anybody doing this?