How is mineral oil produced?
Contents
What is mineral oil? — basic definition and importance
From crude oil to base oil: the refining process
API base oil groups — Group I to Group V
Mineral oil production stages — step by step
Core equipment used in production
The role and types of additives
Blending technology
Quality control and international standards
Mineral oil types and applications
Environmental effects and sustainable production
Waste oil recycling
Frequently asked questions (FAQ)
Conclusion
What is mineral oil?
Mineral oil is a hydrocarbon-based lubricant obtained by putting crude oil through advanced refining steps such as atmospheric and vacuum distillation, hydrogenation and solvent refining. It is used in engines, machinery, turbines, gearboxes and hydraulic systems to reduce friction, dissipate heat, protect metal surfaces and carry contaminants away. Around 40 billion liters of mineral oil are consumed worldwide each year, which places it among petroleum derivatives' most strategic processed products. In Türkiye, growth in the automotive, energy, construction and production sectors raises the demand for mineral oil every year.
Core functions of mineral oil
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Lubrication: lowers the coefficient of friction between metal surfaces and so prevents wear.
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Cooling: absorbs the heat generated by friction and carries it out of the system.
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Cleaning: removes carbon, soot and deposits from piston, cylinder and gear surfaces.
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Protection: shields metal surfaces against oxidation, rusting and corrosion.
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Sealing: fills the small gaps between engine parts and prevents gas from escaping.
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Power transmission: transmits pressure in hydraulic systems and so transfers mechanical power.
2. From crude oil to base oil: the refining process
Mineral oil production begins with the processing of crude oil. The chemical composition of the crude directly determines the quality of the lubricant. Paraffinic crude oils are preferred for mineral oil production because of their low pour point and high viscosity index (VI).
2.1 Atmospheric distillation
Crude oil first enters a distillation column at atmospheric pressure. Heated to roughly 350–400°C, it separates into fractions with different boiling points: LPG and naphtha as light fractions, kerosene and gas oil as middle fractions, and heavy fuel oils and mineral oil precursors as heavy fractions.
2.2 Vacuum distillation
The heavy residue left from atmospheric distillation is distilled again under vacuum (roughly 1–15 mmHg) so that it does not break down at high temperature. This step separates the high-boiling hydrocarbon fractions known as vacuum gas oil (VGO), and these fractions are the feedstock for base oil production.
2.3 Solvent refining (Group I production)
The fractions obtained by vacuum distillation are treated with solvents such as furfural or NMP (N-methylpyrrolidone). This step selectively removes aromatic hydrocarbons and so improves the viscosity index. The product obtained is Group I base oil.
2.4 Hydrocracking (Group II & III production)
Fractions treated with hydrogen gas at high pressure (70–200 bar) and temperature (300–450°C) change their molecular structure. Hydrocracking removes sulfur, nitrogen and aromatic compounds, raises the paraffin content and makes high VI values possible (≥120 for Group III).
2.5 Dewaxing
Two main methods are used in this step, which lowers the pour point of base oils. In solvent dewaxing, solvents such as methyl ethyl ketone (MEK) or toluene/methyl isobutyl ketone (MIBK) precipitate the solid wax crystals, which are then filtered out. In catalytic dewaxing, long-chain n-paraffins are isomerized over zeolite catalysts into branched isomers; this lowers the pour point and preserves the VI.
3. API base oil groups
The American Petroleum Institute (API) classifies base oils into five groups according to saturate level, sulfur content and viscosity index:
Mineral oil production stages
Raw material intake and storage
Crude oil or finished base oil reaches the facility in certified tankers or through pipelines. Incoming quality control covers density (API gravity), sulfur content, viscosity, and water and salt content. Approved raw materials are held in atmospheric steel storage tanks, either floating roof or fixed roof.
Base oil production and supply
Large integrated facilities produce their own base oil, while independent blending plants buy base oil from suppliers certified for Groups I–V. A certificate of conformity to API, NLGI or the customer specification is requested for every base oil batch.
Additive preparation
Additives are usually supplied as concentrated additive packages. For special applications, individual raw materials such as antioxidants, detergents and EP additives are weighed out in the proportions set by the formulation team. Some additives are dissolved in heated mixing tanks.
Blending
Blending is the heartbeat of mineral oil production. Automatic gravimetric or volumetric dosing systems feed base oil and additives into the mixing tank in the calculated proportions. Industrial mixers — propeller, agitator or static mixer — are used at this stage, and temperature control, usually 50–80°C, is critical for a homogeneous distribution.
Intermediate quality control
An intermediate sample is taken after blending, and critical parameters are tested in the laboratory: viscosity (ASTM D445), viscosity index (ASTM D2270), pour point (ASTM D97), flash point (ASTM D92), total base number (TBN — ASTM D2896) and total acid number (TAN — ASTM D664).
Filtration
The product passes through coarse and fine filter systems, generally 1–25 µm pore size, to remove solid particles and traces of water. Vacuum dehydration or coalescer filtration is applied for some high-specification products.
Final quality control and certification
The product goes through the full test package against API, SAE, ACEA or OEM specifications such as BMW Longlife, VW 504.00 and Mercedes 229.5. Once the results are approved, a Certificate of Analysis (CoA) is issued.
Packaging and dispatch
The product is filled on automatic filling lines into 1 L, 4 L, 20 L or 208 L drums, or into IBC (Intermediate Bulk Container) tanks. The product name, SAE viscosity grade, API service category, production date and batch number are printed on the package. Large volumes are transferred straight from the storage tanks into road or rail tankers.
Core equipment used in production
A professional mineral oil production facility has the following core equipment:
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Storage tanks: atmospheric steel tanks or pressure vessels for raw material and finished product. Domestic manufacturers such as Aces Process supply fixed roof, floating roof and heated tank solutions.
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Vacuum distillation unit: a low-pressure column system for separating heavy fractions.
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Hydrogenation reactor: stainless steel or chrome-molybdenum steel reactors working at high pressure and temperature.
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Blending vessels: heated and insulated mixing vessels fitted with an industrial agitator.
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Additive dosing system: automatic gravimetric or volumetric dosing systems.
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Heat exchangers: plate or tubular exchangers for heating or cooling process streams.
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Filtration units: multi-stage filtration systems for removing sediment, moisture and particles.
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Filling and packaging lines: automatic weighing, filling, capping and labeling units.
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Laboratory equipment: viscometer, flash point tester, spectrometer, Karl Fischer moisture meter.
7. Blending technology
Blending is the critical process that brings base oil and additives together according to the target formulation. Two main blending methods are used:
7.1 Batch blending
This is the most widely used method. Measured quantities of base oil and additives are transferred into the mixing tank in sequence and stirred for a set time until the mixture is homogeneous. It allows flexible formulation changes, so small and medium-sized facilities prefer it.
7.2 Continuous (inline) blending
Dosing takes place simultaneously into static mixers installed in the pipeline. This suits large-scale production that needs high capacity and a fixed formulation. The level of automation is high, and the system is controlled by PLC/SCADA.
Critical blending parameters
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Temperature control (50–80°C): lowers viscosity and speeds up the dissolution of the additives.
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Mixing time: varies between 30 minutes and 4 hours according to the formulation and the tank size.
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Mixer type and speed: applications that call for low shear force use a slow propeller, while those that call for high homogeneity move to a high-shear mixer.
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Nitrogen blanket: contact with air is prevented, which minimizes the risk of oxidation.
8. Quality control and international standards
Compliance with international standards is mandatory in mineral oil production. The main reference standards are:
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API (American Petroleum Institute): the SN Plus and SP categories for engine oils, GL-4 and GL-5 for gear oils.
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ACEA (European Automobile Manufacturers' Association): categories such as A3/B4, C3 and E9 for European vehicles.
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SAE (Society of Automotive Engineers): viscosity classification — SAE 5W-30, 10W-40, 80W-90 and so on.
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ISO (International Organization for Standardization): industrial oil viscosity grades such as ISO VG 46 and ISO VG 68.
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OEM specifications: vehicle manufacturer approvals such as VW 504.00/507.00, BMW Longlife-04, Mercedes-Benz 229.51 and Ford WSS-M2C929-A.
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NLGI (National Lubricating Grease Institute): grease consistency classification, from 000 to 6.
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TSE (Turkish Standards Institution): domestic conformity within the framework of the TS EN standards.
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ISO 9001:2015: quality management system certification.
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ISO 14001:2015: environmental management system certification.
9. Mineral oil types and applications
9.1 Automotive oils
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Engine oils (SAE 5W-30, 10W-40, 0W-20): protect the internal surfaces of gasoline, diesel and hybrid engines.
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Gearbox oils (GL-4, GL-5): lubricate the gear pairs in manual and automatic transmissions.
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Steering hydraulic fluids: transfer pressure in power steering systems.
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Brake systems: DOT 3/4/5 class hydraulic brake fluids.
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Greases (NLGI 2): for wheel bearings, running gear and suspension components.
9.2 Industrial oils
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Hydraulic oils (ISO VG 32, 46, 68): construction machinery, presses and hydraulic cylinder systems.
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Turbine oils: the bearing and gear systems of steam and gas turbines.
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Compressor oils: piston and screw air compressors.
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Metalworking oils: cutting, turning, milling, grinding and drawing operations.
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Heat treatment oils: hardening, tempering and annealing processes.
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Transmission and slideway oils (ISO VG 220, 320): heavy industry gear systems.
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Transformer oils: insulation and cooling in electrical transformers.
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Food grade oils (NSF H1): white mineral oils for equipment that can come into contact with food.
10. Environmental effects and sustainable production
Mineral oil production carries a number of environmental risks, but modern facility design and management systems reduce those risks considerably.
Main environmental risks and their solutions
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VOC emissions: the volatile organic compounds released during blending and filling are minimized by closed systems and vapor recovery units (VRU).
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Wastewater management: oil residues in refining water are removed by oil–water separators and biological treatment, and the treated water is reused.
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Soil contamination: sealing coatings and double-walled tank design reduce the risk of leakage from tankers.
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Carbon footprint: recovering process heat with waste heat exchangers lowers energy consumption by 15–25%.
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Packaging waste: recyclable HDPE or metal containers are preferred.
11. Waste oil recycling
Used mineral oils left in the environment form a thin film on surfaces and do serious harm to aquatic and land ecosystems. The recycling process runs as follows:
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Collection and sorting: used oils are freed from water, fuel mixtures and foreign matter.
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Pre-treatment: physical and chemical separation removes the coarse contaminants.
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Re-refining: vacuum distillation and hydrofinishing reprocess the oil into base oil that reaches Group II quality.
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Energy recovery: fractions that do not meet the quality standards are used to generate energy in controlled incineration plants.
In Türkiye, used oil recycling is carried out by licensed companies within the framework of the Regulation on the Control of Waste Oils of the Ministry of Environment, Urbanization and Climate Change.
12. Frequently asked questions (FAQ)
What is the difference between mineral oil and synthetic oil?
Mineral oil is a hydrocarbon-based product obtained by refining crude oil (Groups I–III). Fully synthetic oil is polyalphaolefin (PAO — Group IV) or ester-based (Group V) oil produced by chemical processes. Synthetic oils offer a broader operating temperature range, a longer drain interval and better oxidation resistance, but they cost more.
Why does the viscosity index of a mineral oil matter?
The viscosity index (VI) shows how far the viscosity of an oil changes with temperature. Oils with a high VI hold a stable viscosity at both low and high temperature. This property is a critical performance factor, above all in engine and turbine oils exposed to very large temperature swings.
How is the SAE viscosity classification read?
In multigrade oils such as 10W-40, '10W' states the cold viscosity (W = winter) and '40' the kinematic viscosity at 100°C. A low W number means good flow at low temperature, and a high second number means sufficient film thickness at high temperature.
Which licenses are needed to set up a mineral oil production facility?
In Türkiye, mineral oil production calls for a mineral oil production license from EPDK (the Energy Market Regulatory Authority), an EIA (Environmental Impact Assessment) certificate and a capacity report from the Ministry of Industry. Sales on the domestic market additionally require a market placement certificate and OEM approvals.
Mineral oil production is a process that demands serious engineering: crude oil goes through complex refining steps, base oils are classified, additives enrich them, and rigorous quality control procedures turn them into the final product.
Correct facility design, suitable equipment selection and compliance with international standards decide both product quality and sustainable production. Aces Process supplies engineering and manufacturing services at every stage of a mineral oil facility, from process design to mechanical fabrication.
Author:
Industrial Design Engineer