ISO 13357-1:2025

Overview

ISO 13357-1:2025 - Petroleum products - Determination of the filterability of lubricating oils - Part 1: Procedure for oils in the presence of water - defines a laboratory method to evaluate the filterability of mineral-based lubricating oils when contaminated with water. The procedure is intended primarily for oils up to ISO viscosity grade (VG) 100 (ISO 3448), with provisions to test heavier oils (VG 150, 220, 320) using coarser membranes. The standard describes test setup, reagents, membranes, measurement stages and acceptance criteria, and includes an alternative gravimetric technique (Annex B).

Key topics and technical requirements

• Scope and limitations
  • Applies to mineral-based oils; fluids such as some fire‑resistant fluids can be incompatible with the test membranes.
  • Not suitable for oils containing insoluble or partially soluble additives (some viscosity index modifiers or friction modifiers) or very large molecular species.
• Two-stage test principle
  • Stage I: Comparison of mean flow rate with initial flow rate to assess early membrane plugging tendency.
  • Stage II: Ratio of initial flow rate to flow rate near 200–300 ml filtered; more sensitive to gels and fine silts.
  • Results are typically the average of three determinations.
• Apparatus and consumables
  • Stainless-steel filtration funnel assembly, 47 mm mixed-cellulose-ester membrane filters.
  • Membrane pore sizes: 0.8 µm for VG ≤ 100; 3.0 µm for VG > 100 (heavy-duty oils).
  • Measuring cylinders (ISO 4788 compliant), compressed dry gas (air or nitrogen), water conforming to ISO 3696 grade 3, isopropanol and light aliphatic hydrocarbon wash solvents.
  • Effective filtration area and membrane batch consistency requirements are specified.
• Measurement techniques
  • Volumetric timing method described in main text.
  • Gravimetric alternative provided in Annex B.
• Precision and test validity
  • The standard addresses sampling, apparatus preparation, calculation of filterability ratios and assessment of validity.

Practical applications and users

• Who benefits
  • Lubricant manufacturers, independent test laboratories, OEMs, hydraulic system designers, maintenance engineers and quality control teams.
• How it’s used
  • Evaluate oil suitability for systems where water contamination is likely (hydraulic systems, paper machines, rolling mills).
  • Predict filtration performance and risk of filter plugging, inform filter selection and maintenance strategy.
  • Support R&D, quality assurance, acceptance testing and failure analysis related to filtration behaviour.

Related standards

• ISO 13357 series (other parts)
• ISO 3448 (viscosity classification)
• ISO 3170 (sampling)
• ISO 3696 (water for laboratory use)
• ISO 4788 (graduated measuring cylinders)
• ISO 6614 (water separability)

Keywords: ISO 13357-1:2025, filterability, lubricating oils, presence of water, membrane filters, ISO viscosity grade, gravimetric techniques, hydraulic oils, filtration test procedure.