Oil used In Automotive Air Conditioners

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MINERAL OIL: Mineral oil is used in all old R12 (Freon) systems. It has worked well for years and would be the recommended lubricant for all R12 applications. R12 has a high affinity for mineral oil, meaning it takes mineral with it as it travels through the system. Mineral oil does not mix with R134a and there for not usable. I have specialized in air conditioning work and have been getting mineral oil on my skin for years with no ill effects that I know of.

PAG OIL (Polyalkylene Glycol Oil): PAG oil is used OEM (Original Equipment Manufactures) in their R134a systems. PAG oils will soften paint which can be a major problem. PAG oils are harsher on o-rings and seals. PAG oils may cause skin irritations. PAG oil seems to give my skin problems when I work with it. I get a mild rash even from the vapors. It is recommended that you always wear protective gloves and goggles while handling or servicing a system with PAG oil. PAG oil is very hydroscopic (absorbs moisture from the air) and must be kept in closed metal containers.

POLYOL ESTER OIL (Retrofit Oil)

Polyol Ester oil (Ester for short) or retrofit oil as its' sometimes called is the preferred oil to use when you are performing a retrofit. Ester oil is recommended by most after market manufactures and rebuilders. Ester oil mixes with and is compatible with mineral oil. Ester oil can be used with R12 and R134a refrigerants. Ester oil is not as harsh to o-rings, seals and paints as PAG oils. This is the oil that comes in or is supplied with the compressors that come from Everco, Murray, and Four Seasons. When you are doing major repairs you could prepare the vehicle for later retrofit.

You could:

Flush the heat exchangers and hoses.
Add an R134a compatible drier/accumulator.
Service with Ester oil along with R12.
Then add special service fittings, label and R134a when R12 becomes unavailable.

I have been told that Poyol Ester oil does not provide as good of lubrication as mineral oil when used with R12.

RECOMMENDATIONS

OEM Manufactures: They use and recommend PAG oil. If you add oil to a OEM system use PAG oil.

AFTER MARKET MANUFACTURES

Four Seasons, Everco and Murray are the main aftermarket A/C parts suppliers.

They recommend that you retrofit only when you have too.
They supply and recommend Ester oil for use when you do retrofits. Also sense its compatible with all R12/R134a compressors it could be used in a R12 system that may be retrofitted latter.
They recommend that you put 1/2 of the oil in the compressor and the other 1/2 in the accumulator or evaporator if it does not have an accumulator. This starts the system with good oiling of the compressor.
They supply and recommend a solvent for flushing air conditioning systems. It Contains HFCF-141b which is a non-hazardous/non-regulated solvent for automotive use.
They recommend that you use the same oil that's already in the system when you are just adding oil. In a system that contains PAG oil you should add PAG oil.

Four Seasons Everco and Murray have hot lines that can provide you with their catalogues, views and recommendations.

Four Seasons Hot Line 1-800-433-7508

Pn 59009 Ester Oil 100 vis.
Pn 59012 Ester Oil 150 vis.
Pn 59015 Ester Oil 68 vis.
Pn 59030 Flushing Solvent 141b
Pn 59031 Capture Tank
Pn 59032 Capture Hose & Fitting Kit
Four Seasons has a oil capacity and viscosity recommendations in their catalog.

Everco & Murray Hot Line 1-800-325-8886 (Choice: 2, 6)

Pn 409500 Ester Oil 100 vis.
Pn 409517 A/C Flush Solvent
Pn 409920 Capture Tank
Pn 409921 Capture Hose & Fitting Kit

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