Car refrigerant & oil filling quantities

Here you will find useful information and handy tips relating to refrigerant and oil filling quantities for air-conditioning systems in vehicles.

Refrigerant and compressor oil are two essential substances for any air-conditioning system. It is also crucial to ensure the correct filling quantities. Scroll through this page and find out about the different variants of refrigerant and compressor oils. You can also find important information on refilling refrigerant and a link to the refrigerant and oil filling quantity manual.

Important safety information
The following technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for use by suitably qualified personnel only.



There are still numerous vehicles on the market with air-conditioning systems originally designed for refrigerant R12. 2001 marked the official final end of R12 in vehicle air-conditioning systems. Ever since then, R12 systems had to be converted during maintenance or repair work. R134a was and is used as replacement refrigerant besides several "drop-in" refrigerants (refrigerant mixtures).


Even today, the conversion from R12 to R134a is still an ongoing topic in the area of classic and modern classic cars as well as in several non-EU countries.


In the course of conversion, the system must be checked for leak tightness. Leaks must be corrected beforehand. All components should be checked for function and damage. The filter dryer is to be replaced. Sealing rings should be replaced. In addition, the mineral oil of the R12 system is to be replaced with PAG or PAO oil. In the course of this replacement it is also recommended to flush the air-conditioning system.


R134a has a high GWP (global warming potential) of 1430. With the current EC Directive 2006/40/EC it was decided to only use refrigerants with a GWP of less than 150 in the future.


Air-conditioning systems in vehicles of class M1 (passenger cars, vehicles with up to 8 passenger seats) and class N1 (commercial vehicles with a permissible total weight of up to 3.5 metric tons) for which a type approval was issued within the EU as of January 1, 2011, can therefore no longer be filled with R134a. As of January 1, 2017, vehicles filled with R134a are no longer entitled to receive initial registration approval. R134a can, however, continue to be used to carry out service and maintenance work on existing R134a systems. R1234yf with a GWP of 4 shall be used as new refrigerant. Other refrigerants can also be used, however, provided their GWP value is below 150. Only in time will it become apparent if all vehicle manufacturers agree on a single refrigerant, or whether different refrigerants will be used.


This, of course, also impacts workshops and their service personnel. As such, it appears that purchasing new service units is something that cannot be avoided. Separate measures with respect to storing and handling the new refrigerants must certainly also be observed.


When refilling refrigerant and performing any work on the refrigerant circuit, please observe the following:

  • Always wear protective goggles and gloves! Under normal atmospheric pressure and ambient temperatures, liquid refrigerant evaporates so quickly that any physical contact with the skin or eyes can cause the tissue to freeze (risk of blindness).
  • If direct physical contact has been made, thoroughly rinse the affected areas with a generous supply of cold water. Do not rub. Seek the medical attention of a doctor immediately!
  • The workplace must be well ventilated for working on refrigerant circuits. Breathing in high concentrations of gaseous refrigerant can cause dizziness and even suffocation. Do not work on the refrigerant circuit from an inspection pit. As gaseous refrigerant is heavier than air, it can collect in high concentrations there.
  • Do not smoke! Refrigerant can be broken down into poisonous substances if it contacts cigarette ash.
  • Do not introduce an open flame or hot metal in the immediate vicinity of refrigerant. Doing so can cause lethal gases to form.
  • Never allow refrigerant to leak out into the atmosphere. If the refrigerant reservoir or air-conditioning system is opened, its contents will escape under high pressure. The extent of the pressure depends on the temperature. The higher the temperature, the higher the pressure.
  • Do not expose any components of the air-conditioning system to heat. After paintwork, do not heat vehicles above 75°C (drying furnace). If this cannot be avoided, drain the air-conditioning system beforehand.
  • When removing the service tubes from the vehicle, do not point the connections toward your body. Refrigerant residues may leak.
  • When cleaning the vehicle, do not point the steam-jet cleaner directly onto parts of the air-conditioning system.
  • Never change the factory setting of the adjusting screw on the expansion valve.


Which filling quantities apply to which vehicles? Our latest manual for refrigerant and oil filling quantities provides the answer for the most common vehicle types.

1 Condenser with round pipes
2 Condenser with flat pipes
3 Condenser 16 mm
4 Condenser 23 mm
5 Rear engine
6 Front engine
7 Expansion valve, old type
8 Expansion valve, new type
9 See sticker in engine compartment
n.a. Overall quantity for system not known or not specified by manufacturer – if appropriate, see sticker in the engine compartment or on the compressor
q Quantity depends on version – see sticker in the engine compartment or on the compressor
w Condenser 18 mm
e Condenser 20 mm
f Thickness of the condenser’s flat pipe
g Without oil radiator
h Condenser module, dryer integrated in the condenser
i Orga/manuf. no. /see information near A/B pillar
VIN = Vehicle Identification Number

Notes Commercial Vehicles

(1) OE Behr Hella Service
Compressor Unicla: PAG OIL UNIDAP PAO 68 of PAG ISO 46
Compressor Zexel: PAG OIL ZEXEL ZXL 100PG PAO 68 of PAG ISO 46
Compressor Sanden: PAG OIL SANDEN SP 20 PAO 68 of PAG ISO 100
Compressor Nippondenso: PAG OIL ND 8 PAO 68 of PAG ISO 46
Compressor Kiki: FUCHS RENISO PAG 46” PAO 68 of PAG ISO 46
Oil filling quantity ʼn .a.” = quantity unknown or not specified by the manufacturer

Refrigerant analysis using the Inspector

Check of the air-conditioning system for impurities using the Inspector.


03:34 min


Product features

PAG oils are fully synthetic, hygroscopic oils based on polyalkylene glycol. Numerous vehicle and compressor manufacturers use them in different viscosities at their plants for air-conditioning systems that work with R134a refrigerant.


PAG oils mix well with R134a and are suitable for lubricating and sealing the air-conditioning systems in most passenger and commercial vehicles. When using PAG oils, ensure that you select the correct viscosity classification (PAG 46, PAG 100, PAG 150). Observe the specifications and approvals of the vehicle manufacturers.

Further details

The disadvantage of PAG oils is that they are hygroscopic, i.e. they absorb and bind humidity from the ambient air. For this reason, opened oil containers must be resealed immediately and once opened, the remaining oil cannot be stored indefinitely. This is particularly important for the fresh oil containers at the air-conditioning service unit.


Product features

PAO Oil 68 is not hygroscopic, i.e. unlike other oils, it does not absorb humidity from the ambient air. It can be used as an alternative to the various PAG oils that are offered for R134a. As a result, you only need to stock one type of oil, instead of three different PAG oils. PAO Oil 68 helps to increase the performance of the air-conditioning system. The oil is available without an added contrast agent (PAO Oil 68) or with it included (PAO Oil 68 Plus UV).

Usage/effect of PAO Oil 68

The molecules of the PAO Oil 68 adhere to all surfaces in the system, force out other molecules, and remain as a thin layer on the surface of the system components.


Due to the fact that the molecules do not try to bond with each other, this oil layer is just one molecule "thick". Therefore, in contrast to many other oils, there is no risk of oil collecting in the evaporator and the resulting loss of cooling output when PAO Oil 68 is used.


Due to the fact that PAO Oil 68 only slightly bonds with the refrigerant, just a small part of the oil circulates through the system. The rest stays where the oil is actually needed – in the compressor. An oil film in the components improves the seal and reduces the friction between the moving parts in the compressor.


This reduces the operating temperature and the wear. This plays an important role in operating safety and the reduction of noise and also ensures lower run-times and less energy consumption by the compressor.

Usage/effect of PAO Oil 68 Plus UV

PAO Oil 68 Plus UV has the same advantageous properties as PAO Oil 68.


It is additionally enhanced with a concentrated, highly effective contrast agent that is used for UV leak detection.


The advantage of the low Vol % concentration of the contrast agent is that all the properties of the oil are retained and there are no negative effects on system components or service devices whatsoever.


To achieve a sufficient effect during troubleshooting, 10 Vol % of the system oil quantity is already quite adequate. This corresponds e.g. to only 18 ml of PAO Oil 68 Plus UV when the total system oil quantity is 180 ml.


In addition, PAO Oil 68 Plus UV can also be used for filling the whole system without there being any negative effects.

Can PAO Oil 68 be used for conversions? Is PAO Oil 68 compatible with other oils?

PAO Oil 68 doesn't have any harmful effects on fluoroelastomer materials, such as hoses or seals, and is ideally suited for converting from R12 to R134a refrigerant.


Since PAO Oil 68 is compatible with many other lubricants and refrigerants, PAO Oil 68 can be used both for refilling and replacing the entire system oil quantity. Due to the independent molecular structure and density, PAO Oil 68 mixes to a certain extent with other oils, but separates from them again when it "comes to rest", and does not enter into a longer-term compound.


This guarantees that the necessary viscosity of the oils is maintained and there is no change in the overall viscosity (see Figs. 1 and 2). Thanks to its unique combination of highly refined, synthetic oil and special performance-enhancing additives, PAO Oil 68 has a very wide operating range (-68 to 315°C).

How was PAO Oil 68 Plus UV tested?

PAO Oil 68 Plus UV was tested by the manufacturer and independent institutes. Thus, for example, chemical stability was tested in connection with the refrigerant and different O-ring materials on the basis of the so-called "sealed tube test", corresponding to the norm ASHRAE 97.


All the tests showed a positive result, confirming that negative effects on components in the vehicle air-conditioning system or the air-conditioning service station can be excluded. Thus PAO Oil 68 Plus UV can be filled directly into a component e.g. the compressor, or via the air-conditioning service station into the refrigerant circuit.

Can PAO Oil 68 be used where there are humidity problems?

PAO Oil 68 is not hygroscopic, i.e. unlike other oils, it does not absorb humidity from the ambient air. This means that humidity problems, e.g. icing of components or formation of acids, can be counteracted simply by using PAO Oil 68. The application possibilities and the storage ability of PAO Oil 68 are much greater compared to conventional oils.

Special features and properties

  • No risk of oil collecting in the evaporator and the associated deterioration in cooling performance
  • An oil film in the components improves the seal
  • Reduction in the friction between the components
  • Reduced energy consumption by the compressor
  • Unique combination of highly refined, synthetic oil and special performance-enhancing additives
  • Very wide operating range (-68 to 315 °C)
  • Low Vol % concentration of the highly active contrast agent PAO Oil 68 Plus UV, which means the system components and service devices are protected and wear is reduced


Product features

Electric air-conditioning compressors in hybrid vehicles are powered by an internal electric motor that operates in the high voltage range. The compressor oil in these compressors comes into contact with the electric motor coil, amongst other things.


As such, it has to satisfy particular requirements:

  • It must not have any adverse effect on the materials used in the compressor.
  • It must be resistant to electrical short circuits to a certain degree.


The POE oil from Behr Hella Service meets these requirements.


  • Can be used on all hybrid vehicles with electrical compressors that are filled with POE oil at the plant.
  • Bottled in spotgun cartridges, which gives it maximum protection against humidity (problem: POE oil is hygroscopic).

Further details

  • Using the spotgun (cartridge press), it can either be filled straight into the vehicle (with the aid of an adapter hose with low-pressure connection) or into the oil tank on the air-conditioning service device
  • 120 ml spotgun cartridge
  • Each individual cartridge is sealed in an aluminium bag
  • The aluminium bag also contains a smaller bag with desiccant (drying pellets) to optimally protect the oil against humidity


Type of oil Use Remark
PAG oils
for refrigerant R134a

Different grades of PAG oil with different flow properties (viscosities) are available for use with refrigerant R134a.

PAG oils are hygroscopic. As a result, any cans that have been opened cannot be stored for prolonged periods.

Standard PAG oils are not suitable for R1234yf refrigerant and electrically driven air conditioning compressors
for refrigerant R1234yf

Different PAG oils are also available with different flow properties (viscosities) for use with the R1234yf refrigerant.

What makes these PAG oils from Behr Hella Service so special is that they are not only suitable for use with refrigerant R134a.

PAG oils are hygroscopic. As a result, any cans that have been opened cannot be stored for prolonged periods.

PAG Oil YF is suitable for both of the refrigerants R1234yf and R134a
PAO oil
for refrigerant R134a and other refrigerants R123yf and other refrigerants

Can be used as an alternative to the various PAG oils that are offered for R134a (has the advantage of not being hygroscopic, i.e. unlike other oils, it does not absorb humidity from the ambient air).

The 3 different grades of PAO oil offered by Behr Hella Service (AA1, AA2, and AA3) can be used in conjunction with numerous different refrigerants (see product overview).

PAO oil AA1 Clearversion (without leak detection agent) can also be used with the new refrigerant R1234yf and also in electrically driven compressors in hybrid vehicles.
POE oil
for refrigerant R134a
Can be used on all hybrid vehicles with an electric compressor that are filled with POE oil at the plant (there are also electrically driven compressors for hybrid vehicles that are filled with a special PAG oil at the plant). Not suitable for refrigerant R1234yf