Base Oil — Group I / II / III CAS 64742-54-7
Chelora Chemicals supplies Group I, Group II and Group III base oils across the full viscosity range to lubricant blenders, grease makers and process oil users worldwide. Every consignment leaves with a batch-specific COA covering viscosity, viscosity index, sulphur, saturates and colour, the current SDS and full export documentation.
Also known as: Base oil · Base stock · SN 150 / SN 500 · N150 / N500 · Group I / II / III · Lube base oil
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Price, lead time and a sample COA for Base Oil — Group I / II / III, usually within one working day. We ship worldwide.
Request a Quote Email the DeskDocumentation
- Batch-specific COA (viscosity, VI, sulphur, saturates, colour)
- Safety Data Sheet (SDS)
- Transport and export documents
- Third-party inspection on request
- Certificate of origin
What is Base Oil — Group I / II / III?
Base oil is the fluid that makes up 70 to 99% of a finished lubricant, with additives providing the rest. Its quality sets the baseline for everything the finished oil can do.
The API classifies base stocks into groups. Group I is solvent refined with under 90% saturates or over 0.03% sulphur; Group II is hydrotreated with over 90% saturates and low sulphur; Group III is severely hydrocracked with a viscosity index above 120.
That classification matters commercially because engine oil specifications have moved steadily toward Group II and III, while Group I remains important in industrial oils, greases and process applications.
Within each group, viscosity grade — SN 150, SN 500 and so on — determines which blends the oil suits. Group and viscosity grade together define the product.
Why base oil grade matters
- Viscosity index. Higher VI means less viscosity change with temperature, which is what modern engine oils require.
- Saturates and sulphur. Determine oxidation stability and additive response; the basis of the API group classification.
- Volatility. Noack volatility limits oil consumption in modern engines and is tighter in each successive specification.
- Additive response. Group II and III respond differently to additives than Group I, so blends cannot simply be swapped.
How Base Oil — Group I / II / III is Manufactured
Base oils are made by refining the vacuum gas oil cut, with the processing severity determining the group.
- Vacuum distillation. Vacuum gas oil is fractionated into viscosity cuts from the atmospheric residue.
- Solvent extraction. Furfural or NMP extraction removes aromatics, giving Group I base stock.
- Solvent dewaxing. MEK and toluene dewaxing removes wax to reach the required pour point, producing slack wax as co-product.
- Hydrotreating. Severe hydrogen treatment saturates aromatics and removes sulphur and nitrogen, giving Group II.
- Hydrocracking and isodewaxing. Severe hydrocracking with catalytic dewaxing produces Group III with VI above 120.
- Finishing. Hydrofinishing and clay treatment set final colour and stability.
Typical Commercial Specification
Figures below are representative of a Group II SN 150 base oil. Each group and viscosity grade has its own data sheet — tell us the blend and we will send the matching one.
| Parameter | Typical Value |
|---|---|
| Appearance | Clear bright liquid, free of suspended matter |
| Kinematic viscosity at 100 °C | 4 – 12 cSt depending on grade |
| Viscosity index | 95 to 105 Group I; 100 to 120 Group II; 120+ Group III |
| Saturates | Under 90% Group I; over 90% Group II and III |
| Sulphur | Over 0.03% Group I; under 0.03% Group II and III |
| Pour point | Typically −9 to −15 °C |
| Flash point | Typically 200 to 240 °C |
| Colour (ASTM) | 0.5 to 2.0 depending on group |
| Noack volatility | To grade, critical for engine oil blends |
| Aniline point | To grade, indicating solvency |
Physical & Chemical Properties
| Property | Value |
|---|---|
| Composition | Refined hydrocarbon mixture, mainly paraffinic and naphthenic |
| Appearance | Clear bright liquid, pale yellow to water white |
| Density | About 0.85 to 0.88 g/cm³ at 15 °C |
| Kinematic viscosity at 40 °C | About 20 to 110 cSt depending on grade |
| Viscosity index | 95 to 140 depending on group |
| Pour point | Typically −9 to −15 °C |
| Flash point | Typically 200 to 240 °C |
| Oxidation stability | Improves markedly from Group I to Group III |
| Solvency | Group I highest, Group III lowest — relevant for additive and seal compatibility |
| Water solubility | Practically insoluble |
| Incompatibilities | Strong oxidisers |
Behaviour in the process
The differences between groups are what matter in formulation:
- Solvency falls as group rises. Group III dissolves additives and swells seals less than Group I, which affects formulation and sometimes seal compatibility.
- Oxidation stability rises as group rises. Removing aromatics and sulphur extends drain intervals, which is why specifications moved that way.
- Volatility matters in engine oils. Noack volatility limits have tightened with each specification generation, favouring Group II and III.
- Brightstock is Group I only. Heavy brightstock for greases and gear oils comes from Group I refining, which is why its decline matters.
Base Oil Groups and Alternatives
Base oils are bought by API group and viscosity grade, and the finished lubricant specification normally dictates both.
| Material | Origin / type | When it is the right choice |
|---|---|---|
| Group I | Solvent refined, VI 95 to 105 | Industrial oils, greases, process oils and brightstock |
| Group II | Hydrotreated, VI 100 to 120 | Mainstream engine and industrial oils — the volume standard |
| Group III | Hydrocracked, VI 120+ | Premium and synthetic-labelled engine oils with long drain intervals |
| Group IV (PAO) | Polyalphaolefin from 1-decene | True synthetics for extreme temperature and premium applications |
| Group V | Esters, naphthenics and others | Specialty applications and as co-base stocks for solvency |
Stated plainly: the group is normally fixed by the finished oil specification rather than chosen freely. Where there is latitude, Group III buys oxidation stability and low volatility, and Group I buys solvency and brightstock availability.
Industries We Supply Base Oil — Group I / II / III To
Base oils serve automotive, industrial, marine and process markets.
Where Base Oil — Group I / II / III is Used
Automotive and industrial lubricants take the majority of base oil, with process oils and greases behind them.
Choosing a group
Finished lubricant specifications normally dictate the group: modern passenger car engine oils with long drain intervals and low volatility requirements effectively require Group II or III, while greases and many industrial oils still work best on Group I because of its solvency and the availability of brightstock. Where latitude exists, it is usually in industrial and process applications.
Group I decline
Group I refining capacity has been closing steadily in Europe and elsewhere as engine oil demand moved on. This matters most for brightstock, the heavy cut used in greases and gear oils, which only Group I refining produces. Grease makers in particular should plan supply rather than assume availability.
Need a specific grade, purity and packing format?
Tell us the grade, the API group, viscosity grade and whether brightstock is required, the packing format you can receive and the annual quantity. We will come back with a price, a lead time, a sample COA and the full documentation set.
Quality Control & Testing
Every lot is released against a batch-specific Certificate of Analysis with the group-defining properties, so your blending laboratory can release against the actual material.
- Kinematic viscosity at 40 and 100 °C — the primary grade measure.
- Viscosity index — calculated from both viscosities, defining the group boundary.
- Saturates and sulphur — the API group classification criteria.
- Pour point and flash point — confirming low-temperature and safety performance.
- Colour and appearance — confirming finishing quality and freedom from contamination.
- Noack volatility — for engine oil base stocks, where volatility limits apply.
Common Process Problems & Likely Causes
When base oil causes trouble, it is usually group substitution, viscosity drift or contamination. This table is the shortcut our technical desk works through before anyone opens a complaint file.
| Symptom | Likely cause | What to check |
|---|---|---|
| Finished oil viscosity off target | Base oil viscosity grade or blend ratio | Viscosity figures against the blend calculation |
| Additive package not dissolving | Group III solvency lower than the formulation assumed | Group and aniline point; a co-base stock may be needed |
| Seal shrinkage in service | Low solvency base stock in a formulation designed for Group I | Group selection and seal swell additive |
| Oxidation stability below specification | Group I used where Group II or III was qualified | Group classification and saturates figure |
| Oil consumption high in engine tests | Noack volatility above the specification limit | Volatility figure against the engine oil specification |
| Colour darker than expected | Finishing quality or contamination in transfer | Colour result and tank cleanliness |
Packaging, Storage & Shipping
- Standard packing. 200 L drums, 1000 L IBCs, flexitanks, ISO tank containers and bulk parcel cargoes.
- Storage. Clean, dry, covered storage; keep water out, since water contamination is the most common base oil quality problem.
- Temperature. Ambient storage; heavier grades pump better when warm, and heating may be needed for brightstock in cold weather.
- Contamination control. Dedicated tanks and lines per group where possible; cross-contamination between groups affects finished oil approvals.
- Water control. Use desiccant breathers on tanks; water ingress causes hazing and promotes oxidation.
- Filtration. Filter on receipt where cleanliness specifications apply, as for hydraulic oils.
- Shelf life. Typically 24 to 60 months in sealed, dry storage.
- Transport classification. Not classified as dangerous goods for transport.
Hazards & Safe Handling
Refined base oils have very low toxicity and are not classified as dangerous goods. The practical concerns are slip hazards, hot oil and prolonged skin contact.
- Low toxicity. Severely refined base oils are not classified as carcinogenic; the refining process removes the polycyclic aromatics that caused historical concerns.
- Slip hazard. Spilled oil is a serious slip hazard; clean up promptly and use absorbent.
- Hot oil burns. Blending and process operations run hot; thermal burns are the realistic process hazard.
- Prolonged skin contact. Can cause dermatitis and folliculitis; use gloves and change oil-soaked clothing promptly.
- Oil mist. Where mist is generated, exposure limits apply and extraction is required.
- Used oil. Used lubricating oil is a different and more hazardous material than fresh base oil, with its own classification.
- Environment. Harmful to aquatic life; contain spills and prevent entry to drains and watercourses.
Regulatory & Compliance Notes
Base oils are unregulated for transport, with refining severity determining their health classification. The notes below are orientation rather than legal advice.
- GHS classification. Severely refined base oils are generally not classified as hazardous; poorly refined mineral oils carry a carcinogen classification.
- Refining severity. The EU carcinogen classification applies unless the refining history is known or DMSO extract is below 3% by IP 346.
- Transport. Not classified as dangerous goods. Standard packaged and bulk cargo documentation applies.
- Food grade applications. White oils and food machinery lubricants require separate pharmacopoeial or NSF registration.
- Engine oil specifications. API, ACEA and OEM approvals define which base stocks may be used in a qualified formulation.
- REACH and inventories. Registered under EU REACH as petroleum substances with defined refining descriptions.
We Supply Base Oil — Group I / II / III Worldwide
Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Base Oil — Group I / II / III from India and from partner sources to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation, transport paperwork and freight so the material arrives ready to use.
- Incoterms. EXW, FOB, CIF, CFR and DAP quoted to suit your purchasing terms and freight arrangements.
- Ports. Regular shipments through Nhava Sheva (JNPT) and Mundra, with other ports arranged where routing and cargo rules allow.
- Documentation. Commercial invoice, packing list, certificate of origin, COA, SDS and the transport declaration issued as a complete set.
- Flexible volumes. From a pallet of drums up to repeat bulk shipments on a supply contract.
- Supply continuity. Because we are independent of any one producer, a plant turnaround or a shipping disruption at one source does not have to become your stock-out.
Buying Base Oil — Group I / II / III from Chelora
We are an independent sourcing and supply partner. For base oils that means settling three things at enquiry: the API group and viscosity grade your formulation requires, whether brightstock is needed, and the packing and tankage arrangements that keep groups separated.
- Documentation on every lot. Batch-specific COA (viscosity, VI, sulphur, saturates, colour), plus SDS and the full transport paperwork.
- Analysis before commitment. Representative analysis shared ahead of a commercial order so your lab can qualify the material.
- Quantities. From a pallet of drums through to full bulk shipments on contract supply.
- Grade matching. Group I, II or III base oil at the viscosity grade, VI and volatility your formulation or approval requires.
- Inspection. Independent third-party inspection available at loading when the contract requires it.
- Related products. Paraffin Wax, Naphtha, Linear Alpha Olefins and other feedstocks alongside Base Oil — Group I / II / III from one supplier.
How ordering works
- Send the enquiry. Product, grade or purity, quantity, destination port and the Incoterm you buy on. If you have a spec sheet, attach it — it saves a round trip.
- We quote. Price, lead time, packing format and a sample COA, normally within one working day.
- Qualify the supply. For first orders or critical applications, we share the analysis and handling documentation so your technical and safety teams can sign off before you commit.
- Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
- Allocation and QC. Material allocated and released against a batch-specific COA, with an independent inspection where the contract calls for it.
- Ship and document. Filled, labelled and loaded with the full export document set, and tracked through to arrival.
Base Oil — Group I / II / III — Common Questions
The questions our technical desk is asked most often about Base Oil — Group I / II / III. If yours isn't here, call or email and you will reach someone who knows the chemistry.
What is the CAS number of base oil?
Base oils are petroleum substances rather than single compounds. Solvent-refined heavy paraffinic distillate is commonly given CAS 64742-54-7, with EC number 265-157-1, and base oils are classified under HS code 2710.19.
What are base oils used for?
They make up 70 to 99% of finished lubricants: engine oils, gear and transmission fluids, hydraulic and turbine oils, greases, metalworking fluids and rubber and textile process oils.
Do you supply base oils worldwide?
Yes. Chelora Chemicals supplies and exports Group I, II and III base oils worldwide — across Asia Pacific, Europe, the Middle East, Africa and the Americas, as well as throughout India, in drums, IBCs, flexitanks, ISO tanks and bulk.
What is the difference between Group I, II and III?
Group I is solvent refined with under 90% saturates or over 0.03% sulphur and VI 95 to 105. Group II is hydrotreated with over 90% saturates, low sulphur and VI 100 to 120. Group III is severely hydrocracked with VI above 120.
How are base oils manufactured?
By vacuum distilling the gas oil cut, then either solvent extracting and dewaxing for Group I, severely hydrotreating for Group II, or hydrocracking with catalytic dewaxing for Group III, followed by hydrofinishing.
Can I substitute Group II for Group I?
Not in a qualified formulation without reformulation. Group II has better oxidation stability but lower solvency, which affects additive dissolution and seal swell. Engine oil approvals are granted against specific base stocks.
Why is Group I supply tightening?
Because Group I refining capacity has been closing as engine oil specifications moved toward Group II and III. This matters most for brightstock, the heavy cut used in greases and gear oils, which only Group I refining produces.
What is viscosity index and why does it matter?
It measures how much viscosity changes with temperature. A higher VI means more stable viscosity across the operating range, which is what modern engine oils require and what separates the API groups.
Are base oils hazardous?
Severely refined base oils have very low toxicity and are not classified as dangerous goods or as carcinogenic. Poorly refined mineral oils do carry a carcinogen classification, which is why refining history and DMSO extract testing matter.
What is Noack volatility?
A measure of how much oil evaporates at 250 °C. Engine oil specifications limit it to control oil consumption, and the limits have tightened with each generation, favouring Group II and III base stocks.
How should base oil be stored?
In clean, dry, covered storage with desiccant breathers, with groups kept in separate tanks. Water contamination is the most common base oil quality problem and cross-contamination between groups affects approvals.
What packing sizes are available?
200 L drums, 1000 L IBCs, flexitanks, ISO tank containers and bulk parcel cargoes. Orders run from a pallet of drums up to repeat bulk cargoes on contract supply.
Ready to source Base Oil — Group I / II / III?
Send us your specification, grade and annual volume. You will get a price, a realistic lead time and a sample COA from someone who understands what the material has to do in your process — delivered anywhere in the world.