4.1 Refinery and re-refinery feedstock and the processes to which the feed is subject determine the composition of the base stock produced. Once produced, other potential sources of variation include storage, transportation and blending. It follows that lubricating base oils will be of variable chemical composition. For this reason, characterization criteria for hydrocarbon lubricant base oils are frequently chosen from properties such as those listed in Table 1 and/or Table 2. If specification limits are established, they are usually related to the intended use of the base oil.

4.2 The consistent performance of hydrocarbon lubricant base oils is a critical factor in a wide variety of applications such as engine oils, industrial lubricants, and metalworking fluids. In addition, in many of these applications humans are exposed to the base oils as a component of a formulated product such that health or safety considerations may need to be addressed. This guide suggests a compilation of properties and potential contaminants that are understood by those knowledgeable in the manufacture and use of hydrocarbon lubricants to be significant in some or all applications. A discussion of each of the suggested properties and potential contaminants is provided in Appendix X2, with each listed alphabetically within four categories.

4.3 The test methods, base oil properties, and potential contaminants suggested are those that would likely be useful in many common situations, although it is recognized that there are specific applications and situations that could have different requirements. Performance testing related to a specific application may serve as the basis for acceptability.

4.4 Issues such as frequency of testing and the specifics of how the test results are to be applied are not addressed in detail. It is the responsibility of the buyer and seller to determine and agree upon the implementation of this guide. This guide serves as a basis for that discussion.

1.1 This guide suggests physical, chemical, and toxicological test methods for characterizing hydrocarbon lubricant base oils derived from various refining processes including re-refining used oils and refining crude oil. This guide does not contain limits nor does it purport to cover all tests which could be employed; rather, it represents the first step in better describing important parameters of lubricant base oils affecting lubricant performance and safe handling. Tests have been identified to characterize the composition and performance of base oils in addition to verifying their consistency. Undesirable components have also been identified with a range of typical levels. These are not limits. It is the responsibility of the buyer and seller to determine and agree upon the implementation of this guide.

1.2 This guide applies only to base oils and not to finished lubricants.

1.3 Base oils containing detectable levels of esters, animal fats, vegetable oils, or other materials used as, or blended into, lubricants are not covered by this guide.

1.4 This guide is relevant to base oils composed of hydrocarbons and intended for use in formulating products including automotive and industrial lubricants. Although not intended to cover all base oil viscosity grades, this guide does cover the majority of viscosities that would be used in both automotive and industrial oil formulations. These base oils would typically have a viscosity of approximately 2 mm²/s to 40 mm²/s (cSt) at 100 °C (50 SUS to 3740 SUS at 100 °F).

1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.