Engineering tools · Bearing lubrication

Oil & Bearing Viscosity Analyser | Revolution Synthetic Oil

Two related questions in one tool: how stable is this oil across temperature (viscosity index), and is it actually thick enough for this bearing at its operating temperature (viscosity ratio κ)?

Enter the oil's ν40 and ν100 once — it drives the VI calculation, the viscosity–temperature curve, and the κ curve for your bearing.

ASTM D2270 · ASTM D341 · SKF κ
01 Oil
cSt
cSt
—
02 Bearing
—
03 Operating conditions
—
VISCOSITY INDEX (ASTM D2270)
–
03580110200
Enter both viscosities to see the result.
VISCOSITY RATIO κ = ν / ν₁ (AT OPERATING TEMP)
–
01246+
Enter the bearing and speed to see the lubrication regime.
MEAN DIA. dm
–
mm
RATED ν₁
–
cSt
ACTUAL ν @ T
–
cSt
04 Viscosity & κ vs temperature
Enter both viscosities to plot the curves.
Viscosity ν(T) — left axis Viscosity ratio κ(T) — right axis, fixed 0.5–6 κ = 1 (= ν₁) — where the curves cross Operating temperature

Viscosity index uses the piecewise quadratic method from ASTM D2270 Appendix X2, matched to the standard's own reference tables to within approximately 0.1%.

Viscosity at temperature uses the ASTM D341 (Walther) relation fitted through your two entered points: log₁₀(log₁₀(ν + 0.7)) is linear in log₁₀(T in kelvin). Extrapolation far outside 40–100 °C — particularly below the oil's cloud point or above about 150 °C — becomes progressively less reliable.

Rated viscosity ν₁ = 45000·n⁻⁰·⁸³·dm⁻⁰·⁵ for n < 1000 r/min, and 4500·n⁻⁰·⁵·dm⁻⁰·⁵ for n ≥ 1000 r/min (n in r/min, dm in mm), per the SKF General Catalogue diagram. κ = ν/ν₁. Because ν₁ depends only on speed and bearing size, it is constant with temperature — so the κ curve is the viscosity curve rescaled by 1/ν₁, shown on its own axis rather than as independent data.

The bearing lookup covers deep groove ball (60/62/63/64), miniature (603–693), tapered roller (302xx), spherical roller (222xx/223xx), angular contact (72xx/73xx), self-aligning (12xx/13xx) and cylindrical roller (N/NU/NJ/NUP 2xx/3xx) bearings. It's a reference table, not a substitute for the manufacturer's dimension sheet.

© 2026 UNIQOL LTD. All rights reserved. This calculator, its formulas' implementation, bearing dimension tables, and design are original work and may not be copied, redistributed, or claimed as another party's work without permission.