Quick answer: PAG 46 and PAG 100 are both polyalkylene glycol (PAG) compressor oils used in belt-driven automotive A/C systems — the number is the ISO viscosity grade, not a quality ranking. Choose by compressor type and the vehicle specification: swash-plate and axial-piston compressors, the majority of belt-driven units, take PAG 46, while DENSO through-vane (TV08, TV12, TV14) and SV06 scroll compressors take PAG 100. A PAG 46 oil such as Sunice P46 or DENSO ND-OIL 8 is not the grade those vane and SV06 units specify, and PAG 100 oil is equally wrong for a swash-plate compressor. Refrigerant compatibility is the first filter — see our guide to using one PAG 46 oil for R134a and R1234yf — and viscosity matching is the second.
Both grades are PAG oils: synthetic lubricants designed to mix with HFC refrigerants and return through the system to the compressor. The numbers refer to the ISO viscosity grade, which is based on kinematic viscosity measured at 40 °C. Measured values from product data sheets put the difference in plain numbers: Sunice P46, an ISO VG 46 oil, measures 46.3 mm²/s at 40 °C, while DENSO ND-OIL 9, an ISO VG 100 oil, measures 95 mm²/s at 40 °C with 11.8 mm²/s at 100 °C and a viscosity index of 114.
"PAG 100 is thicker" is true but the wrong mental model. The grade is set by the compressor manufacturer to match bearing clearances, operating speeds and oil-return behaviour of a specific compressor family. OE quick-reference charts list PAG oils in a series that runs 46, 100 and 150, and every chart adds the same instruction: verify the viscosity with the vehicle or compressor manufacturer. Thicker does not mean better protection — it means the wrong film thickness for parts that were designed around a specific grade.
PAG oils are also hygroscopic: they absorb moisture from the air, which is why service containers are sealed and resealed promptly regardless of grade.
Belt-driven mechanical A/C compressors fall into two broad families, and the oil specification follows the family.
Swash-plate and axial-piston compressors. These are the most common belt-driven compressors in passenger vehicles. DENSO specifies its PAG 46 oils for this family: ND-OIL 8 in R134a systems, and ND-OIL 12 where an R1234yf-rated PAG 46 is needed. Sunice P46, a Japanese PAG 46 from Japan Sun Oil Company, is specified for belt-driven swash-plate and piston compressors and carries R134a and R1234yf coverage in one grade.
Rotary vane and specific scroll compressors. Through-vane rotary compressors and the SV06 scroll series are a different specification: DENSO specifies its PAG 100 oil, ND-OIL 9, for through-vane (TV08, TV12, TV14), through-vane scroll (TVS) and SV06 compressors in R134a systems. ND-OIL 9 is an ISO VG 100, double-end-capped PAG made in Japan. A PAG 46 grade specified for swash-plate or piston compressors — such as Sunice P46 or ND-OIL 8 — is not the oil these units specify.
Electric compressors on hybrid and EV platforms are a third, separate case: they use POE oil (DENSO ND-OIL 11), not a PAG grade at all. That distinction belongs to electric-compressor service and is outside the PAG 46 versus PAG 100 question.
So the practical rule: identify the compressor type first, then match the viscosity the manufacturer specifies for that type. Refrigerant compatibility is the first filter — an R134a-only PAG must not be used with R1234yf refrigerant — and viscosity matching is the second. Both filters are covered in our PAG 46 refrigerant compatibility guide.
| A/C Compressor Oil | Grade and Viscosity | Compressor Type It Matches | Refrigerant Coverage |
|---|---|---|---|
| Sunice P46 | PAG 46 (ISO VG 46), 46.3 mm²/s at 40 °C | Belt-driven swash-plate and piston compressors | R134a and R1234yf |
| DENSO ND-OIL 8 | PAG 46 (ISO VG 46), approx. 46 mm²/s at 40 °C | Piston, rotary, scroll and sliding-vane belt-driven compressors | R134a |
| DENSO ND-OIL 9 | PAG 100 (ISO VG 100), 95 mm²/s at 40 °C | Through-vane TV08/TV12/TV14, TVS and SV06 scroll compressors | R134a |
| DENSO ND-OIL 12 | PAG 46 (ISO VG 46) | Belt-driven mechanical compressors | R1234yf, backward-compatible with R134a |
| DENSO ND-OIL 11 | POE (not a PAG grade) | Electric compressors on hybrid and EV platforms | R134a and R1234yf |
One boundary case is worth noting: DENSO's own selection note states that through-vane and TVS compressors may require PAG 100 (ND-OIL 9) instead of PAG 46, even where an R134a PAG 46 is otherwise used in the same vehicle range. When the compressor model is known, check its specification rather than assuming the grade from the refrigerant alone.
Compressor manufacturers design the lubrication around a specific viscosity. Running a grade that is too thin can reduce the load-carrying oil film under high-speed or high-load operation, which shows up as wear and compressor noise and shortens service life. Running a grade that is too thick increases internal drag and heat, slows oil return through the system, and raises the risk of foaming and liquid slugging in the compressor.
Neither failure is instant, which is why wrong-grade fills can run for a season before the compressor fails. The safe position is simple: use the viscosity the vehicle or compressor specification calls for, and treat "it is roughly the same oil" advice with caution — the PAG series is not interchangeable by judgement.
Confirming the correct grade is a five-step check that protects the compressor and the vehicle warranty.
A: Only if the compressor specification says PAG 46. DENSO specifies PAG 100 (ND-OIL 9) for its through-vane and SV06 scroll compressors; a PAG 46 oil such as Sunice P46 or ND-OIL 8 is not that grade. Check the compressor model and its service specification before filling.
A: Both are PAG lubricants for mechanical A/C compressors, but they are different ISO viscosity grades — around 46 mm²/s versus around 95–100 mm²/s at 40 °C — matched to different compressor families. The number is a viscosity class, not a quality rating.
A: Identify the compressor type and check the vehicle or compressor specification. As a DENSO example, swash-plate and piston compressors take PAG 46 (ND-OIL 8 for R134a; ND-OIL 12 or Sunice P46 where R1234yf-rated PAG 46 is needed), while through-vane TV08/TV12/TV14 and SV06 compressors take PAG 100 (ND-OIL 9). When in doubt, request the technical data sheet with your inquiry.
A: Yes, PAG 100 is the higher-viscosity grade, but thicker does not mean better. The compressor is designed around a specific grade; the wrong viscosity can cause wear (too thin) or drag, foaming and poor oil return (too thick).
A: Mixing A/C compressor oils is not recommended — viscosity and additive packages differ between grades and brands. If the oil in the system is unknown, follow the manufacturer's flush-and-refill procedure rather than topping up.
A: The viscosity grade follows the compressor type; the refrigerant determines the oil's additive compatibility. R1234yf mechanical compressors use R1234yf-rated PAG 46 oils such as ND-OIL 12 or Sunice P46, while ND-OIL 9 (PAG 100) is an R134a-only grade. See our guide on using PAG 46 oils across R134a and R1234yf systems.
Sources: DENSO Aftermarket service guidance on compressor oil and refrigerant mixing (2017); DENSO technical data for the ND-OIL series (retrieved 2026-09-08); FJC OE viscosity PAG oil quick-reference chart covering the 46/100/150 series (retrieved 2026-09-08); MACS Mobile A/C Society service guidance; Four Seasons chemical compatibility guidance; Japan Sun Oil Company, Ltd. product information sheet for Sunice P46 (retrieved 2026-09-07). Viscosity values quoted from these data sheets; always follow the vehicle or compressor manufacturer specification for the exact application.
Editorial review: Reviewed by Qishanr Technical Team, September 8, 2026. This article is updated when compressor oil specifications materially change.
Sunice P46 gives workshops and fleets a Japanese PAG 46 oil for belt-driven swash-plate and piston A/C systems — one grade stocked for both R134a and R1234yf vehicles. Send your refrigerant and compressor details for specification confirmation, or view DENSO ND-OIL 9 for PAG 100 applications.
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