MIL-PRF-46170 Kinematic Viscosity Chart

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MIL-PRF-46170 kinematic viscosity vs temperature in degrees F, compared with MIL-PRF-83282

The red line is one product, not the whole fluid. It is the Castrol Brayco Micronic 883 typical viscosity (one product), a piecewise ASTM D341 interpolation through five manufacturer values from −54 °C to 204 °C (−65.2 °F to 399.2 °F). Y-axis is logarithmic.

Between neighbouring points the line is straight in ASTM D341 coordinates. Nothing is extrapolated. There is no value between −40 °C and 40 °C, between 40 and 100 °C, or between 100 and 204 °C, so every span between two points is interpolation only.

All 46170 values are manufacturer “typical” values for single lots (not measurements made for this site, no uncertainty stated). Other products are separate markers: AeroShell Fluid 61 (2021 data sheet, MIL-PRF-46170E), AeroShell Fluid 61 (AeroShell Book, MIL-PRF-46170D) and RADCOLUBE FR170. Black crosses are the limits of MIL-PRF-46170E Table I (maximum at −40 and 40 °C, minimum at 100 °C), not measurements. The blue MIL-PRF-83282 series is the NADC-79248-60 measurement of that fluid (1980 reference lot, lot and revision not stated), copied unchanged from the MIL-PRF-83282 viscosity page.

Data from: Castrol Brayco Micronic 883 data sheet (curve); MIL-PRF-46170E Table I (limits); other product data sheets as listed under Sources; NADC-79248-60 Table 1 (83282 comparison).

Toggle data sets by clicking the legend.

MIL-PRF-46170 Viscosity Calculator
Degrees (°F):
Degrees (°C):
Kinematic Viscosity (Brayco Micronic 883 typical)
mm²/s (= cSt): 
Centistokes (cSt): 
Stokes (cm²/s): 
m²/s: 
in²/s: 
ft²/s: 
MIL-PRF-83282 (comparison)
Kinematic (cSt): 
46170 / 83282 ratio: 

Kinematic viscosity is valid −54 °C to 204 °C (−65.2 °F to 399.2 °F), from the piecewise ASTM D341 interpolation through the Castrol Brayco Micronic 883 typical values. These are typical values for one product and one lot, so another MIL-PRF-46170 product can differ (at −40 °C the four products on this page span 2047 to 2488 cSt). The MIL-PRF-83282 row is the NADC 1980 reference lot, valid over the same range. There is no dynamic viscosity output: see the note below.

Viscosity of MIL-PRF-46170 Fire-Resistant Hydraulic Fluid
About This Data

MIL-PRF-46170E (NATO code H-544, military symbol FRH) limits the kinematic viscosity to 2600 mm²/s at −40 °C (maximum), 19.5 mm²/s at 40 °C (maximum) and 3.4 mm²/s at 100 °C (minimum). It has no −54 °C limit. Viscosity index improvers and pour point depressants are not allowed. The specification gives only these limits. It has no table of viscosity against temperature.

The values on this page come from manufacturer data sheets for products printed as qualified to MIL-PRF-46170. All are “typical” values for single lots, with no stated uncertainty. The five points of the Castrol Brayco Micronic 883 sheet (10 June 2021) cover the widest range, −54 to 204 °C, so the line uses that sheet only. The sheet prints the −54 °C row as “−54 °C / 65 °F”. The Fahrenheit value is a typo for −65 °F, so the point is used as −54 °C (−65 °F). The other three products give 3 or 4 points each and stay below 100 °C.

Products differ most when cold. At 40 °C the four sets span 14.7 to 15.6 mm²/s (6 %). At −40 °C they span 2047 to 2488 mm²/s (22 %), and all are below the 2600 mm²/s limit. The older AeroShell Book sheet (MIL-PRF-46170D) and the Castrol sheet give −54 °C values of 15022 and 14650 mm²/s.

The smooth line is a piecewise ASTM D341 interpolation: between neighbouring points it is straight in Y = log10(log10(ν + 0.7)) against X = log10(T°C + 273.15), with ν in cSt, and it passes exactly through every Castrol point. A single D341 line through all five points misfits by +10.9 % at −54 °C and −4.5 % at 40 °C, so it is not used. The range is −54 to 204 °C. Nothing is extrapolated.

Why there is no dynamic viscosity chart. Dynamic viscosity is μ = ν × ρ, so it needs the density at the same temperature. The data sheets print the density at one temperature only, 15.6 °C (relative density 0.848 to 0.859). No source gives density at other temperatures, and the density of this fluid was not estimated from another fluid. The one value that can be given is below. For the fluid’s density and other limits see MIL-PRF-46170 general properties.

Dynamic (Absolute) vs. Kinematic Viscosity
Dynamic (Absolute) Viscosity — μ

Dynamic viscosity measures a fluid’s resistance to shear: the internal force per unit area required to make one layer slide past another. It is independent of density. The SI unit is the pascal-second (Pa·s); the common engineering unit is the millipascal-second (mPa·s), numerically equal to centipoise (cP).

\[ \tau = \mu\,\frac{du}{dy} \]
Kinematic Viscosity — ν

Kinematic viscosity is the ratio of dynamic viscosity to fluid density. The SI unit is m²/s; the common unit is mm²/s, numerically equal to centistokes (cSt). Hydraulic fluid specifications grade viscosity kinematically because viscometers measure time-of-flow under gravity, which naturally yields kinematic viscosity.

\[ \nu = \frac{\mu}{\rho} \quad\Rightarrow\quad \mu\ [\text{mPa}\cdot\text{s}] = \frac{\nu\ [\text{mm}^2/\text{s}] \times \rho\ [\text{kg/m}^3]}{1000} \]
Dynamic Viscosity at 15.6 °C (indicative only)

The Castrol sheet prints a specific gravity of 0.85 at 15.6 °C (7.08 lb/gal). With water at 15.6 °C taken as 999.1 kg/m³, ρ is about 849 kg/m³. The Castrol viscosity at 15.6 °C is not printed. The interpolated value is 39.9 mm²/s, so μ is about 33.9 mPa·s (= cP) at 15.6 °C (60 °F). Treat this as approximate: it uses an interpolated viscosity and a two-digit specific gravity. The relative densities on the four data sheets (0.848 to 0.859) would move it by about −0.2 to +1 %.

Castrol Brayco Micronic 883: Typical Viscosity
Temp (°C) Temp (°F) Kinematic viscosity (mm²/s)

Castrol Brayco Micronic 883 Product Data, 10 June 2021 (ISO 3104 / ASTM D445). Typical values for one lot, no uncertainty stated. The sheet prints the −54 °C row as “−54 °C / 65 °F”; the Fahrenheit value is a typo for −65 °F. Viscosity index 126 (printed).

Specification Limits (MIL-PRF-46170E Table I, p.7)
Temp (°C) Temp (°F) Kinematic viscosity limit (mm²/s) Castrol 883 curve (mm²/s)

These are acceptance limits for the fluid (ASTM D445), not measurements. The last column is the Castrol 883 line on this page at the same temperature, for reference only. The limits are the same in revision D (the AeroShell Book sheet shows them).

Manufacturer Typical Values (not measurements)
Source Temp (°C) Temp (°F) Kinematic viscosity (mm²/s)

Single-lot typical values, no uncertainty stated. The Castrol points are in the first table and are not repeated. Sources: AeroShell Fluid 61 (Shell TDS v1.4, 31 May 2021, printed as MIL-PRF-46170E Type I), AeroShell Fluid 61 (AeroShell Book, printed as MIL-PRF-46170D Type I) and RADCOLUBE FR170 (Radco, printed as MIL-PRF-46170E). The Book sheet and the 2021 sheet are different production lots of the same product and differ by 8 % at −40 °C.

MIL-PRF-46170: Viscosity by Temperature
Temp (°C) Temp (°F) Kinematic (mm²/s) Basis

Values from the piecewise ASTM D341 interpolation through the five Castrol Brayco Micronic 883 typical values. “Typical (printed)” marks the five temperatures on the data sheet. Every other row is interpolation, with no measurement inside its span.

MIL-PRF-46170 vs MIL-PRF-83282

Both are synthetic hydrocarbon fluids without viscosity index improvers. See MIL-PRF-83282 viscosity and MIL-PRF-83282 general properties. The Castrol 46170 line is up to 27 % thicker than the NADC 83282 reference lot at −54 °C (1.2 times at −40 °C) and within 7 % of it from 40 to 204 °C. The two curves cross near −4 °C and again near 106 °C. The 46170 limit at −40 °C (2600 mm²/s) is above the 83282D limit (2200 mm²/s). The NADC 83282 lot is more viscous at 38 °C than current 83282D products (14.2 to 15.0 mm²/s at 40 °C), which are close to the 46170 products (14.7 to 15.6). For the petroleum fluids 46170 replaces in ground equipment, see MIL-PRF-6083 and MIL-PRF-5606.

Temp (°C) Temp (°F) 46170 kinematic, Castrol 883 (mm²/s) 83282 kinematic, NADC (mm²/s) Ratio 46170 / 83282

46170: Castrol Brayco Micronic 883 typical values, piecewise D341 interpolation. 83282: the piecewise D341 interpolation of the MIL-H-83282 column of NADC-79248-60 Table 1 (Conte & Hammond, 1980, DTIC ADA081597), copied unchanged from the MIL-PRF-83282 viscosity page. Both over −54 to 204 °C. The 83282 lot and revision are not stated in the report; the 46170 line is a typical value for one lot of one product. The comparison is therefore indicative.

Sources
  • Castrol, Brayco Micronic 883 Product Data, 10 Jun 2021. Brayco Micronic 883 data sheet (hosted copy of the maker’s PDF). Typical kinematic viscosity at −54, −40, 40, 100 and 204 °C (ISO 3104 / ASTM D445). Printed claim: “meets and is qualified under military specification MIL-PRF-46170E, Type I, Amendment 2”. Accessed 29 Oct 2026.
  • Shell, AeroShell Fluid 61 (NA) Technical Data Sheet, v1.4, 31 May 2021. AeroShell Fluid 61 TDS (reseller copy). Typical kinematic viscosity at −40, 40 and 100 °C (ASTM D445). Printed specification: “MIL-PRF-46170E Type I”. Accessed 29 Oct 2026.
  • Shell, The AeroShell Book, hydraulic fluids pp. 6.24 to 6.27, AeroShell Fluid 61. AeroShell Fluid 61 (AeroShell Book pages) (reseller copy; edition year not printed). Typical viscosity at −54, −40, 40 and 100 °C. Printed specification: “MIL-PRF-46170D Type I”. Accessed 29 Oct 2026.
  • Radco Industries, RADCOLUBE FR170 data sheet (MIL-PRF-46170E). RADCOLUBE FR170 data sheet (reseller copy). Typical viscosity at −40, 40 and 100 °C (ASTM D445). Accessed 29 Oct 2026.
  • US Department of Defense, MIL-PRF-46170E, Performance Specification: Hydraulic Fluid, Rust Inhibited, Fire Resistant, Synthetic Hydrocarbon Base, NATO Code No. H-544, 30 May 2013. everyspec.com. Table I viscosity limits, p.7. Accessed 29 Oct 2026.
  • A. A. Conte Jr. and J. L. Hammond, Development of a High Temperature Silicone Base Fire-Resistant Hydraulic Fluid, NADC-79248-60, Naval Air Development Center, Warminster PA, 5 Feb 1980. DTIC ADA081597. apps.dtic.mil/sti/tr/pdf/ADA081597.pdf. Table 1, MIL-H-83282 column (comparison series).

Manufacturer values are single-lot typicals with no stated uncertainty. No primary source for density, specific heat or thermal conductivity of this fluid against temperature was found, so there are no pages for those properties. Data are also listed in tools/mil-prf-46170-sources.json and tools/mil-prf-46170-derived.json.

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