Base Oil

Description and usages:

Almost every lubricant used in plants today started off as just a base oil. The American Petroleum Institute (API) has categorized base oils into five categories (API 1509, Appendix E). The first three groups are refined from petroleum crude oil. Group IV base oils are full synthetic (polyalphaolefin) oils. Group V is for all other base oils not included in Groups I through IV. Before all the additives are added to the mixture, lubricating oils begin as one or more of these five API groups.

Group I

Group I base oils are classified as less than 90 percent saturates, greater than 0.03 percent sulfur and with a viscosity-index range of 80 to 120. The temperature range for these oils is from 32 to 150 degrees F. Group I base oils are solvent-refined, which is a simpler refining process. This is why they are the cheapest base oils on the market.

Specification of Group 1 Base Oil.

SN 65 SN 70 SN 150 SN 500 BS 150
SL.NO Parameter Method Unit Result Result Result Result Result
1 Flash point ASTM D92 °C Min 170 Min 174 Min 200 250 Min 250
2 Pour point ASTM D97 °C Max - 6 Max - 6 Max - 3 -3 Max - 3
3 Density at 15 °C ASTM D1298 Kg/l 0.85 0.85 0.878 0.8947 0.901
4 Viscosity @40°C ASTM D445 cSt Min 8 Min 8.5 Min 29.4 110 Min 450
5 Viscosity @100°C ASTM D445 cSt Min 2.28 Min 2.3 Min 5 11.73 29.5
6 Viscosity Index ASTM D2270 - Min 90 Min 90 Min 92 94 Min 90
7 Color ASTM D1500 - Max 0.5 Max 1.0 Max 2 L 2.5 Max 4
8 Odor Organoleptic - - - - No Foul smell -
9 Appearance Visual - Clear & Bright Clear & Bright Clear & Bright Clear & Bright Clear & Bright

Group II

Group II base oils are defined as being more than 90 percent saturates, less than 0.03 percent sulfur and with a viscosity index of 80 to 120. They are often manufactured by hydrocracking, which is a more complex process than what is used for Group I base oils. Since all the hydrocarbon molecules of these oils are saturated, Group II base oils have better antioxidation properties. They also have a clearer color and cost more in comparison to Group I base oils. Still, Group II base oils are becoming very common on the market today and are priced very close to Group I oils.

N 150 N 500 N 600
SL.NO Parameter Method Unit Result Result Result
1 Flash point ASTM D92 °C Min 200 Min 242 Min 245
2 Pour point ASTM D97 °C -3 Max -12 Max - 12
3 Density at 15 °C ASTM D1298 Kg/l 0.878 0.87 0.87
4 Viscosity @40°C ASTM D445 cSt Min 29.4 Min 110 Min 110.5
5 Viscosity @100°C ASTM D445 cSt Min 5 Min 11 Min 11.6
6 Viscosity Index ASTM D2270 - Min 92 Min 95 Min 95
7 Color ASTM D1500 - Max 2.0 L 0.5 L 0.5
8 Odor Organoleptic - - - -
9 Appearance Visual - Clear & Bright Clear & Bright Clear & Bright

Group III

Group III base oils are greater than 90 percent saturates, less than 0.03 percent sulfur and have a viscosity index above 120. These oils are refined even more than Group II base oils and generally are severely hydrocracked (higher pressure and heat). This longer process is designed to achieve a purer base oil. Although made from crude oil, Group III base oils are sometimes described as synthesized hydrocarbons. Like Group II base oils, these oils are also becoming more prevalent.

SL.NO Parameter Method N 100 N 150 N 250
1 Flash point ASTM D92 224 238 248
2 Pour point ASTM D97 -15 -12 -12
3 Density at 15C ASTM D1298 0.8344 0.8425 0.8454
4 Viscosity @40°C ASTM D445 19.39 34.96 44.81
5 Viscosity @100°C ASTM D445 4.23 6.315 7.409
6 Viscosity Index ASTM D2270 125 132 130
7 ASTM Color ASTM D1500 L0.5 L0.5 L0.5
8 Odor Ol Factor Marketable Marketable Marketable

Group IV

Group IV base oils are polyalphaolefins (PAOs). These synthetic base oils are made through a process called synthesizing. They have a much broader temperature range and are great for use in extreme cold conditions and high heat applications.

Base oil - Group V

Group V base oils are classified as all other base oils, including silicone, phosphate ester, polyalkylene glycol (PAG), polyolester, biolubes, etc. These base oils are at times mixed with other base stocks to enhance the oil’s properties. An example would be a PAO-based compressor oil that is mixed with a polyolester. Esters are common Group V base oils used in different lubricant formulations to improve the properties of the existing base oil. Ester oils can take more abuse at higher temperatures and will provide superior detergency compared to a PAO synthetic base oil, which in turn increases the hours of use.

Remember, whichever base oil you choose, just be sure it is appropriate for the application, temperature range and conditions in your plant.