This part of ISO10414 provides standard procedures for determining the following characteristics of oil-based drilling fluids: drilling fluid density (mud weight); viscosity and gel strength; filtration; oil, water and solids concentrations; alkalinity, chloride concentration and calcium concentration; electrical stability; lime and calcium concentrations, calcium chloride and sodium chloride concentrations; low-gravity solids and weighting material concentrations. The annexes provide additional test methods or examples that can optionally be used for the determination of: shear strength (AnnexA); oil and water concentrations from cuttings (AnnexB); drilling fluid activity (AnnexC); aniline point (AnnexD); lime, salinity and solids concentration (AnnexE); sampling, inspection and rejection (AnnexF); rig-site sampling (AnnexG); cuttings activity (AnnexH); active sulphides (AnnexI); calibration and verification of glassware, thermometers, viscometers, retort kit cups and drilling fluid balances (AnnexJ); permeability plugging apparatus with set-screw secured end cap (AnnexK); permeability plugging apparatus with threaded end cap (AnnexL); elastomer compatibility (AnnexM); sand content of oil-based fluid (AnnexN); identification and monitoring of weight-material sag (AnnexO); oil-based drilling fluid test report form (AnnexP).