Skip to the menu / 본문가기
  • Base oil definition

    SK ZIC

    Viscosity between 10 and 50 obtained by further refining the remaining oil when distilling crude oil at atmospheric pressure It has the function of a lubricant that reduces friction as oil.

    Base oil is the main raw material of all petroleum lubricant products. Like base oil products such as gasoline, kerosene and diesel, Since it is derived from crude oil, it is called "mineral oil-based lubricant". Separately from Base oils obtained through chemical synthesis using the above chemicals as starting materials are called
    “chemical synthetic oil-based lubricants”.

    Complex composition, varying viscosity and ingredient content depending on the manufacturing process, high percentage of finished lubricant The quality

    Base oil classification

    1. American Petroleum Institute Classification-1994

    American Petroleum Institute Classification-1994
    Classification Saturated
    sulfur Viscosity index
    Group Ⅰ < 90% and / or < 0.03% and 80 ≤ Ⅵ 120
    Group Ⅱ ≥ 90% and ≥ 0.03% and 80 ≤ Ⅵ 120
    Group Ⅲ ≥ 90% and ≥ 0.03% and Ⅵ ≥ 120
    Group Ⅳ PAO(Poly Alpha Olefin)
    Group Ⅴ Ester & Others

    The base oils produced by solvent extraction in general mineral oil bases are mainly in Group I, and the base oils produced by hydroforming reforming are in Group II.
    VHVI base oils manufactured by highly hydrocracking reactions such as YUBASE are mainly group III.
    Group IV base oils are PAO (Poly Alpha Olefins) and are synthetic lubricating base oils.
    Group V base oils are other base oils such as esters and glycols, which are synthetic base oils.

    2. Classification by composition

    Classification by composition
    Paraffin, % Naphthen, % Aromatics, %
    Paraffin Base Oil 45~60 20~30 15~25
    Napsen base oil 15~25 65~75 ~10
    Aromatic base oil ~5 60~75 20~25

    Basically, the composition of mineral oil is greatly influenced by the crude oil used for the first time.
    In recent years, however, it is not simply purified by fractionation or extraction.
    Since base oils are often manufactured by reactions such as conversion, the composition of the final base oil product is very different from that of the original crude oil because it is less influenced by crude oil.

    3. Base oil classification according to viscosity index

    Base oil classification according to viscosity index
    Range Classification
    Ⅵ 40 Low Viscosity Index(LVI)
    40 ≤ Ⅵ 80 Medium Viscosity Index(MVI)
    80 ≤ Ⅵ 120 High Viscosity Index(HVI)
    120 ≤ Ⅵ 140 Very High Viscosity Index(VHVI)
    140 ≤ Ⅵ Ulta High Viscosity Index(UHVI)

    Viscosity index refers to the degree of change in viscosity with temperature. The higher the viscosity index, the smaller the change in viscosity with temperature.
    Viscosity index is representative of the quality of base oil. In the case of YUBASE, the viscosity index is over 120 and is divided into VHVI.

    4. Base oil classification by viscosity

    Neutral Number

    Neutral base oil refers to the distillation from the tower during distillation under reduced pressure, and the acidic base oil fraction (atmospheric residue) changed to neutral after purification. Uses the expression Neutral in its meaning.

    Base oil classification by viscosity
    40℃ 100℃
    cSt SUS cSt SUS
    70N 13.3 70.8 3.0 37.0
    100N 21.5 104.0 4.0 39.0
    150N 31.6 148.0 4.9 42.4
    250N 56.1 257.0 6.5 47.0
    500N 107.0 496.0 11.0 64.0
    600N 130.4 604.0 12.1 66.0


    Bright stock is used in the sense that very turbid and black is turned into bright oil. Generally, solvent is used to distill the residue under reduced pressure. Manufactured by De-waxing and Hydro-treating.

    Base oil classification by viscosity
    Bright Stock
    40℃ 100℃
    cSt SUS cSt SUS
    135BS 413.2 1875 28.6 135.0
    150BS 568.0 2632 33.0 155.0
    175BS 654.7 3034 36.0 169.7


    In general, the kinematic viscosity (cSt) value of 100 ° C is added, and in case of YUBASE 4, 100 ° C kinematic viscosity is 4 cSt, and in the case of YUBASE 6, 100 ° C kinematic viscosity is 6 cSt.

  • Manufacture of base oils

    1.Purpose of refining

    Lubricant base oils contain a variety of chemicals, including the following, which are not useful for lube base oils.

    Chemical species useful as lube base oil

    Chemical species useful as lube base oil
    Chemical type Reason
    Iso Paraffin High viscosity index
    Sulfur compounds (thiophenes) Sulfur compounds (thiophenes)

    Chemical species that are not useful as lubricant base oils

    Chemical species that are not useful as lubricant base oils
    Chemical type Reason
    Long Chain Paraffin (Wax Type) High pour point adversely affects low
    temperature performance
    Aromatic compounds Sludge generation, carcinogenic
    Unsaturated compounds Sludge / varnish generation
    Chlorine / Nitrogen Compounds Promote oxidation

    In order to obtain high quality base oil, the process of purification, such as removal, maintenance and conversion of the above species, removes the substances that hinder performance and obtains useful substances.

    2. Manufacture process

    Lubricant base oils can be obtained through a variety of processes, which are different in their quality and properties.
    The basic unit process and function are as follows. In addition, the process flow diagram of YUBASE manufacturing is shown below.

    Lubrication Base Oil Manufacturing Unit Process

    Lubrication Base Oil Manufacturing Unit Process
    Classification Function Kinds
    · Separation of atmospheric residual oil by desired viscosity
    · Viscosity and volatilization performance of base oils are determined
    · Aromatic component and S / N / O removal
    · Ⅵ, Oxidation Stability, Color Improvement
    Solvent Extraction
    · Improved Pour Point by removing Wax (Low temperature performance)
    · Ⅵ decreases slightly
    Solvent Dewaxing
    Catalytic Dewaxing
    · Hydrotreating unsaturated hydrocarbons
    · S / N / O Compound Removal
    · Increases thermal and oxidative stability and brightens colors

    YUBASE Manufacture process

    YUBASE Manufacture process

    Vacuum Distillation Unit, VDU

    Lubricant base oil is a mixture of complex hydrocarbons, and usually has a boiling point above 350 ° C at atmospheric pressure, so the oil cannot be obtained from the CDU separating ordinary petroleum products. Therefore, distillation of crude oil from crude oil under reduced pressure distillation through the so-called 'decompression distillation tower' enables the separation of the basic oil base oil.

    Dearomatic Unit

    The fractions classified in the VDU contain a large amount of Aromatic fractions that impair the viscosity index and oxidative stability and thus undergo a Dearomatic process to remove them.

    • Hydro-Treating

      Hydrogenation in a catalyst-packed reaction tower converts aromatic compounds to saturated hydrocarbons, some of which are also paraffinic compounds. Our HBO (SK500N, SK120BS) uses this process.

    • Hydro-Cracking

      It is similar to hydrotreating, but the operating conditions are more severe, leading to decomposition reactions than conversion reactions, resulting in a higher rate of conversion of aromatic compounds to naphthenic compounds and naphthenic compounds to paraffin compounds than hydrotreating. The low Aromatic content and the higher paraffin content provide a base oil with high viscosity index and excellent oxidation stability. YUBASE uses this process.

    Dewaxing Unit

    Wax, a high-level paraffinic hydrocarbon, reduces the fluidity of the oil at low temperatures and easily coagulates. Dewaxing process is used to remove these wax components.

    • Catalytic Dewaxing Unit

      In the reaction column filled with metal catalyst, hydrogenation reaction is used to convert to Iso-Paraffin with excellent fluidity.

    Hydro-Finishing Unit

    In this process, hydrogen is added in the presence of a catalyst to remove unnecessary substances in the oil, which increases the heat and oxidation stability of the oil and changes the color brightly.

  • Base oil quality factor

    Base oils are complex mixtures of different hydrocarbons and the quality of base oils is governed by many factors.
    Representative quality factors are as follows.

    • SK ZIC


      Volatile volatility

    • SK ZIC


      toxicity / flash point

    • SK ZIC



    • SK ZIC


      color / transparency

    • SK ZIC


      Hydrocarbon Saturation
      Aromatic content
      S / N Compound Content

    • SK ZIC


    • SK ZIC

      Viscosity / Low Performance

      Viscosity vs. Temperature (viscosity index) Low temperature viscosity / Pour point Cloud point

    1. Viscosity and Low Temperature Performance

    The physical properties that represent the viscosity characteristics of base oils are the viscosity index, and the viscosity index is the stability against the change in viscosity of the oil with temperature changes. In general, oils with a high viscosity index have good low temperature viscosity properties (Cold Cranking Simulator, Brookfield viscosity). Low temperature fluidity means resistance to oil flow at low temperatures.
    In general, the higher the content of linear paraffins, the higher the viscosity index, but the higher the pour point. Viscosity index / fluid point characteristics according to hydrocarbon type are as follows.

    Viscosity and Low Temperature Performance
    Viscosity index Pour point
    Normal-Paraffins Very High High
    Iso-Paraffins High Medium
    Naphthenes Medium Low
    Alkyl Benzene Depending on the length of the alkyl group
    Multi-Ring Aromatics Low Low

    2. Oxidative stability

    Oxidation proceeds with oxygen in the air, which is directly related to the life / performance of the oil. Compared to the oxidative stability of aromatic and naphthenes oils, paraffinic oils have superior oxidation stability.

    Oxidative stability
    Viscosity index Pour point
    Normal-Paraffins Very High High
    Iso-Paraffins High Medium
    Naphthenes Medium Low
    Alkyl Benzene Depending on the length of the alkyl group
    Multi-Ring Aromatics Low Low
    SK ZIC

    3. volatility

    Volatility refers to the loss of oil in use. The volatility of a base oil is closely related to the molecular weight distribution or the distillation phase of the base oil. In general, oil in the range of 343-399 ℃ of the distillation point distribution determines the volatility of the base oil.
    Volatility is also related to the hydrocarbon distribution, which is closely related to the oxidative stability of the oil. In general, volatility tends to increase as the hydrocarbon type is paraffin, naphthenic, and aromatic.
    So far, we have looked at the types of hydrocarbons that affect base oil quality factors, their meaning and quality. This is summarized below.

    SK ZIC
    High grade base oil
    Solvent Extraction Hydro-Treating Severe Hydro-Cracking PAO
    Viscosity-Temperature Characteristics Fair Good Excellent Excellent
    Oxidation stability Fair Good Very Good Very Good
    Low volatility (low viscosity oil) Poor Good Very Good Very Good
    Low temperature fluidity Poor Good Very Good Excellent
    Additive compatibility Excellent Very Good Very Good Fair
    SK ZIC

    Base Oil Quality Effect by Hydrocarbon Type

    SK ZIC