Base Oil

Base oil is sold by API group and viscosity grade. API 1509 Appendix E sorts base stocks on three numbers. Group I has less than 90% saturates and/or more than 0.03% sulphur, with a viscosity index of 80 to under 120. Group II has 90% or more saturates, 0.03% sulphur or less, and the same VI band of 80 to under 120. Group III meets the Group II saturates and sulphur limits with a VI of 120 or more. Group I is made by solvent refining and is named SN (solvent neutral): SN150, SN500, SN650. Group II is hydroprocessed and is usually named N or by the refiner's own grade: N70, N150, N500, N600. The number is the old Saybolt viscosity at 100 °F, so SN150 and N150 are roughly the same thickness. Bright stock (BS150) is the heavy residual cut of a Group I plant, made by deasphalting vacuum residue. Almost all bright stock comes from Group I plants, and closures there have tightened it.

Typical figures from refiner data sheets: ExxonMobil's AP/E Core series lists Core 150 (Group I) at 29.0-32.0 cSt at 40 °C, VI 100 minimum, flash 210 °C, pour -12 °C and colour 1.5 maximum; Core 600 at 109-116 cSt at 40 °C, VI 95 minimum, flash 246 °C, pour -6 °C, colour 4 maximum; and Core 2500 bright stock at 30.6-32.7 cSt at 100 °C, VI 95 minimum, flash 294 °C, pour -6 °C, colour 6 maximum. Chevron's Group II test data give 220R at 42.7 cSt at 40 °C and 6.6 cSt at 100 °C, VI 106, and 600R at 108 and 12.2 cSt, VI 103, both with sulphur under 10 ppm and saturates above 99%. CBIL is a commodity brokerage company and brokers Group I and Group II base oils from refineries in South Korea, Singapore, the USA, Spain, Germany, Saudi Arabia (Red Sea side), India, Taiwan and Thailand, and from UAE blending hubs. Origin is proven by the refinery COA and a certificate of origin that both name the producing refinery; a lot blended or re-exported from a UAE hub must show where the base oil was refined. Parcels move in bulk on parcel tankers, in ISO tanks, in flexitanks of about 20-22 t per 20-ft container, or in new steel drums of 180-210 kg. Each lot ships against the refinery COA and SGS or Intertek inspection at the load port. Send the grade, API group, quantity, packing, destination port and payment terms, and the enquiry is screened and worked against them. Figures above are typical values from the ExxonMobil AP/E Core base stocks product data sheet, Chevron's Group II/II+ base oils test data and API 1509 Appendix E; the lot COA governs.