KasperCalc: Skydrol Viscosity

Skydrol Kinematic Viscosity Chart

Data range: −65 °F to 210 °F (−54 °C to 99 °C), the three standard ASTM D445 test temperatures, all four grades.

Data from: Eastman Skydrol product comparison brochure (Publication EASAF7870), per ASTM D445. Y-axis is logarithmic (ASTM D341 double-log scale).

Toggle data sets by clicking the legend.

Skydrol Dynamic (Absolute) Viscosity Chart

Computed from kinematic viscosity × density (μ = ν × ρ). Toggle data sets by clicking the legend. Y-axis is logarithmic.

Density source: Skydrol Density page — LD-4 and 500B-4 use their own digitized curves. Skydrol PE-5 and Skydrol 5 have no published density curve, so each scales the LD-4 curve shape to its own Eastman 25 °C density (0.9927 and 0.9737 g/cc); both are shown dashed to flag the extra uncertainty.

Skydrol Viscosity Calculator

Grade:

Degrees (°F):

Degrees (°C):

Kinematic Viscosity

mm²/s (= cSt):

Centistokes (cSt):

Stokes (cm²/s):

m²/s:

in²/s:

ft²/s:

Dynamic (Absolute) Viscosity

mPa·s (= cP):

Centipoise (cP):

Poise (g/(cm·s)):

Pa·s (Poiseuille):

lbm/(ft·s):

kg/(m·h):

ρ used (kg/m³):

Kinematic Viscosity of Skydrol Phosphate Ester Hydraulic Fluid

About This Data

Eastman's Skydrol product comparison brochure (Publication EASAF7870) publishes kinematic viscosity per ASTM D445 at exactly three temperatures for all four grades: −65 °F (−54 °C), 100 °F (38 °C), and 210 °F (99 °C). Viscosity spans nearly three orders of magnitude across that range, so linearly interpolating in cSt would badly overshoot between anchor points. Instead, this calculator interpolates on the ASTM D341 double-log viscosity–temperature axis — the same straight-line scale viscosity–temperature charts are conventionally plotted on, and the same method already used for the site's Multi-Fluid Property Charts. No extrapolation is performed: inputs outside −65–210 °F return "Out of Range."

Skydrol 500B-4 has by far the highest cold-temperature viscosity of the four grades (2678 cSt at −54 °C), while Skydrol PE-5 and LD-4 stay noticeably thinner in the cold — part of why PE-5 and LD-4 are favored where low-temperature pumpability matters. At the high-temperature end all four grades converge to a narrow 3–4 cSt band.

A separate, denser Eastman technical bulletin (Pub. 7249153C) publishes full viscosity curves for LD-4 and 500B-4 from −100 °F to 220 °F, but that bulletin has not been digitized for this site. The Lee Company's published viscosity chart (already digitized site-wide on the Multi-Fluid Property Charts page) covers a similar range but lumps LD-4 and 500B-4 onto a single shared curve. Interpolating that curve at Eastman's own three test temperatures shows it tracks LD-4 fairly well (within about 4 % at −54 °C, 13 % at 38 °C, and 1 % at 99 °C) but understates 500B-4 badly at low temperature — off by roughly 2.2× at −54 °C, tightening to within a few percent by 99 °C. The Lee chart's separate "Skydrol 7000" curve (used here as the Skydrol 5 density/viscosity proxy where noted) similarly diverges from Eastman's Skydrol 5 numbers by about 2× at 38 °C. Given these gaps, the Lee Company data is treated as a cross-check only, never as the primary source for the curves on this page.

Skydrol — Kinematic Viscosity vs. Temperature

Temp (°F)	Temp (°C)	500B-4	LD-4	PE-5	Skydrol 5
Temp (°F)	Temp (°C)	Kinematic viscosity (cSt)

Source: Eastman Skydrol product comparison brochure (Publication EASAF7870), ASTM D445. These are the three directly published points — no interpolation is applied to this table.

Skydrol — Dynamic Viscosity vs. Temperature

Temp (°F)	Temp (°C)	500B-4	LD-4	PE-5*	Skydrol 5**
Temp (°F)	Temp (°C)	Dynamic viscosity (mPa·s)

Computed: μ [mPa·s] = ν [cSt] × ρ [kg/m³] / 1000, at the three published ASTM D445 temperatures. *PE-5 and **Skydrol 5 have no published density curve; each uses the LD-4 curve shape scaled to its own Eastman 25 °C density (0.9927 and 0.9737 g/cc respectively).

Skydrol Kinematic Viscosity Calculator

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