Tip of the Week – Draining Oil

Things to do and look for when draining oil from a compressor… 1) At what ambient was the comp drained at? Hot = more drained oil, Cold = slow/ less oil. 2) Were the ports / caps removed to prevent a vacuum? 3) Was the oil drained and measured from the cylinder head as well as the compressor body? 4) Please remember that depending on the temp at time of draining that aprox 1/2+ oz will remain in the compressor. 5) When the compressor was drained was the compressor crank turned or rotated? 6) How long was the compressor drained?

Did you know?
Some new compressors can leave the factory without an oil charge but checks and balances in most manufacturer’s processes at several different stations that check precise weights of individual and pallet compressors and electronic monitors at the filling station make it hard to pass through. To be on the safe side always check your new compressor for oil.


How often do compressors fail as a result of “manufacturing defects?” Not very often. According to one compressor manufacturer who examined 75 compressors that had failed and were returned under warranty, only two were found to have manufacturing defects. The rest failed because of problems such as too little oil in the system, air in the system, contaminants in the system, or “installer error.” The latter category included using the wrong type of compressor lubricant, not using enough lubricant, using non-approved flushes to “clean” system parts, and using cross-contaminated refrigerants. Debris left over from a previous compressor failure was the most common cause of repeat compressor failures.
Always use the type of lubricant recommended for specific compressors. This is especially important with rotary vane and scroll-type compressors. A replacement compressor may or may not contain lubricant from the factory. In some cases, the shipping oil must be drained before the compressor is installed. In other cases, the compressor may contain a POE or PAG lubricant that may or may not be compatible with the vehicle requirements. Follow the compressor suppliers installation instructions to the letter to avoid warranty problems later on.
Before adding fresh oil to a system, all the old oil should first be removed. This will prevent cross-contamination of lubricants and reduce the risk of overcharging the system with too much oil (which can cause cooling problems). Always refer to the OEM oil capacity chart for the vehicle application. The following is a list of recommended lubricants for R-134a import compressors:

Behr/Bosch rotary compressors – Ester 100
Behr/Bosch piston compressors – PAG 46
Calsonic V5 – PAG 150;
Calsonic V6 – PAG 46
Diesel/Kiki (Zexel) DKS, DKV DCW – PAG 46
Hitachi (all) – PAG 46
Keihin (all) – PAG 46
Matsushita (all) – Ester 100
Mitsubishi FX80 – PAG 100
Mitsubishi FX105 – PAG 46
Nihon (all) – Ester 100
Nippondenso 6P, 10P, 10PA, 10P08E – PAG 46
Nippondenso SP127, SP134 ; 6E171 – PAG 46
Nippondenso TV series – PAG 125
Panasonic (all) – PAG 46
Sanden SD500 SD700 – PAG 100
Sanden SD710, SDB, TV &TRS – PAG 46
Seik-Seiki (all) – Ester 100