Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Refrigerant Oil: Notes
Refrigerant oil mixes with the refrigerant (about 20 - 40%, depending on compressor type and amount of refrigerant) and circulates constantly in the system, lubricating the moving parts.
Special synthetic refrigerant oils, for example, polyalkylene glycol (PAG) oil, are used in conjunction with R134a air conditioning systems. This is necessary as mineral oil, for example, does not mix with R134a. In addition, the materials of the R134a air conditioning system could be corroded as a result of mixture flowing through the refrigerant circuit under pressure at high temperatures or breakdown of the lubricating film in the compressor. Using non-approved oils can cause the HVAC system to malfunction. Only use approved oils.
Type of oil for R134a in motor vehicles: PAG
Do not store open containers of refrigerant oil because it attracts moisture.
Always keep oil containers sealed.
Do not use old refrigerant oil over again.
Used oil disposal: Volkswagen InfoNet; Operations; Handbooks & Dealer Literature; Service Handbook; 15. Environment Protection. Follow the link "Environment Protection in Market- and Service Operations" under general information; 4. Waste Management; 6. Methods of Disposals; g. Disposing of Used Refrigerant Oil
Used refrigerant oils from systems employing halogenated hydrocarbons (at least one hydrogen atom is replaced, for example, with the halogen elements fluorine, chlorine, bromine or iodine) are to be disposed of as waste subject to special supervision. They are not to be mixed with other oils or substances. Proper storage and disposal must be ensured in line with local regulations, refer to the chemical-climate protection provision and the recycling and disposal regulations in Germany. Different specifications and rules may apply in other countries.
German technical, work safety and accident prevention regulations can be obtained from
Addresses in other countries can be obtained from the relevant authorities.
Ester-based oils are only intended for use in large systems, not in passenger vehicle A/C systems.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.