Is this an ASTM D341 conformity calculation?

No. It implements the disclosed modified Walther equation with a constant 0.7 shift and restricts use to interpolation between 40 °C and 100 °C. Exact ASTM D341 equations and limits require the licensed current standard.

Does it calculate viscosity index?

No. ASTM D2270-24 has its own procedures, tables, equations and scope. A partial homemade table is not used.

Can it estimate pour point?

No. Pour point is a measured property under an applicable test method and is not determined by two viscosity values.

Can it calculate dynamic viscosity?

Not without density at the same temperature and the applicable rheological basis.

Empirical interpolation worksheet

Two-Point Walther Viscosity Interpolation

Interpolate between documented kinematic viscosities at 40 °C and 100 °C using the disclosed modified Walther equation. No VI,pour point,dynamic viscosity or lubricant suitability is inferred.

Interpolation only40–100 °CNot ASTM conformity

Interpolation result

Interpolated kinematic viscosity

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Normalized target

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Reference values ν40 / ν100

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Fit constant A

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Fit constant B

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Empirical interpolation only;not a lubricant selection,fitness or ASTM conformity result.

Implemented relation

log10(log10(ν + 0.7)) = A − B·log10(TK)

ν is kinematic viscosity in mm²/s,TK is absolute temperature in kelvins,and A/B are fitted from the entered40 °C and100 °C points.The0.7-shift modified Walther relation is an empirical engineering model;it is not labelled as the exact current ASTM D341 equation.

Restricted use

Target temperature must be between40 °C and100 °C (104–212 °F);no extrapolation.
Both reference viscosities must exceed2mm²/s and ν40 must exceedν100.
Both values must describe the same fluid,batch/state and compatible measurement basis.
Results close to a specification boundary require uncertainty and decision-rule treatment outside this worksheet.

Non calculé

Viscosity Index:ASTM D2270-24 uses its own procedures,tables/equations and scope.
Pour point:two viscosity points do not determine a pour point.
Dynamic viscosity:density at the same temperature and an applicable rheological basis are required.
ISO VG,film thickness,bearing/gear adequacy,startability,wear,churning or lubricant approval.

Standards boundary: ASTM D341-20(2025) is active and covers equations/charts for liquid petroleum or hydrocarbon products within a limited range from two known viscosity-temperature points.The exact current equations and limits remain NEEDS_LICENSED_SOURCE.ASTM D2270-24 is not partially reimplemented.

Sources d'information

ASTM D341-20(2025) official record; ASTM D2270-24 official record; ISO3104:2023 official record; Leao et al.,Lubricants2018 (published0.7-shift Walther fit between40 and100 °C).