BUYER’S LIBRARY
Compare API Groups I–V, understand SN grades and build a specification that fits your formulation.
API / I — V
Saturates < 90% and/or sulfur > 0.03%.
Commonly used in automotive and industrial lubricant blends. Select the viscosity and solvency profile to suit the formulation.
Classification—not a finished-lubricant approval. Groups IV and V are included for education; their availability is not implied.
| API | Definition | Viscosity index |
|---|---|---|
| I | Saturates < 90% and/or sulfur > 0.03%. | VI ≥ 80, < 120 |
| II | Saturates ≥ 90% and sulfur ≤ 0.03%. | VI ≥ 80, < 120 |
| III | Saturates ≥ 90% and sulfur ≤ 0.03%. | VI ≥ 120 |
| IV | API Group IV consists of PAO base stocks. | — |
| V | All base stocks not included in Groups I–IV. | — |
SN 150 is generally a lighter neutral base oil; SN 500 a heavier neutral. Bright Stock is a high-viscosity blending component. These designations are not SAE engine-oil or ISO finished-lubricant grades. Confirm actual viscosity, VI, pour point and flash point against the producer’s technical data sheet and batch certificate.
TECHNICAL / BASE OILS
A purchasing checklist, not a certificate of conformity. Agree the test method, edition, limits and sampling requirements; confirm results on the producer’s batch COA.
| Property | Method / unit | What the buyer should verify |
|---|---|---|
| Kinematic viscosity | ASTM D445 · mm²/s (cSt) | Specify both 40°C and 100°C, including an acceptable range. A viscosity number without its test temperature is incomplete. |
| Viscosity index · VI | ASTM D2270 · dimensionless | VI describes viscosity–temperature behavior. Compare it with the API group and formulation needs; it is not a viscosity grade. |
| Density | ASTM D4052 / D1298 · kg/m³ | State the reference temperature. Convert kg/m³ to kg/L by dividing by 1,000. Use batch density for the mass-to-volume loading calculation. |
| Pour point & cold behavior | ASTM D97 · °C | Request a maximum pour-point limit and any application-specific low-temperature tests. Pour point alone does not establish pumpability. |
| Flash point | ASTM D92 · °C | Keep the test method with the result. Flash point is not an approved storage or heating temperature; handling follows the supplier SDS. |
| Sulfur, saturates & cleanliness | API 1509 · % mass / agreed tests | Confirm sulfur and saturates for group classification. Separately agree water, contamination, appearance and additive-compatibility requirements. |
No. SN identifies a base-oil designation; SAE 15W-40 is a finished engine-oil viscosity grade. Ask for the actual base-oil viscosity and formulation requirements.
Litres = 1,000 ÷ density in kg/L. At an assumed 0.87 kg/L, one tonne is about 1,149.4 L. This is an arithmetic example, not a certified product density.
Request the producer TDS and SDS, proposed origin, batch COA arrangements, packing specification, quantity basis and named delivery place. Confirm availability and commercial terms in writing.
Technical selection notes
Availability, specifications and commercial terms are confirmed in a written quotation.
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