Base oil is the refined hydrocarbon fluid that a lubricant is built on. It is traded as a commodity in its own right, bought by blenders, grease makers and process-oil users who add their own additive package.
A finished lubricant is base oil plus an additive package, and the split is more lopsided than people expect. A modern passenger-car engine oil is roughly 75 to 85 percent base oil by mass. A straight mineral hydraulic oil can be 98 to 99 percent. A lithium grease is base oil, a thickener and a small additive charge. Additive chemistry attracts the attention, but the base stock sets viscosity, volatility, oxidation life, seal behaviour and cold flow — and it carries most of the cost.
Base oil is made from the heavy vacuum distillate cuts of crude oil, and from the deasphalted residue below them. Crude is distilled at atmospheric pressure, the bottoms go to a vacuum column, and the vacuum gas oil cuts are separated by viscosity into light, medium and heavy neutral streams. What comes off the column is not yet base oil. It still contains aromatics that oxidise, wax that turns the oil solid near ambient temperature, and sulphur and nitrogen compounds. Turning that distillate into a lubricant base stock means removing or converting all three.
The classical route runs the distillate through three steps. Solvent extraction with furfural, N-methyl-2-pyrrolidone or phenol pulls out the aromatic and naphthenic-aromatic molecules, which raises viscosity index and improves oxidation stability; the extract stream leaves the plant as aromatic process oil or rubber extender oil. Solvent dewaxing with a methyl ethyl ketone and toluene mixture chills the raffinate and filters out the wax, which is what sets the pour point; the wax is sold separately as slack wax. Hydrofinishing or clay contacting then corrects colour and removes the last polar compounds. The molecules that leave the plant are the molecules that arrived, minus the ones taken out. The product is a Group I base oil.
The modern route converts rather than separates. Hydrocracking at high pressure and temperature over a catalyst saturates aromatics, breaks and rearranges molecules, and strips sulphur and nitrogen down to trace levels. Catalytic dewaxing or wax isomerisation then converts the wax into branched iso-paraffins instead of filtering it out, which lowers the pour point while keeping viscosity index high. A final hydrofinishing stage saturates whatever aromatics remain. The output is Group II or, at higher severity, Group III. Gas-to-liquid plants arrive at the same place from synthesis gas rather than from crude.
Bright stock does not come off the vacuum column at all. It is made from the vacuum residue, which is first propane deasphalted to remove asphaltenes, then solvent extracted, dewaxed and finished like any other raffinate. It is a residual stock, not a distillate stock, and its molecules are larger and heavier than anything a distillate route produces. That matters commercially. Bright stock is made only in solvent plants, so as Group I capacity has closed worldwide its supply has tightened, and no Group II or Group III plant produces a like-for-like replacement.
Base oil is not a finished lubricant. It carries no detergent, no dispersant, no anti-wear chemistry and no antioxidant beyond whatever natural inhibitors survived refining. Putting an unadditised base stock into an engine or a gearbox will destroy it. It is also distinct from the products that leave the same refinery alongside it: aromatic process oils and rubber extender oils are the extract stream rather than the raffinate; transformer oil is a separately specified product carrying dielectric requirements that base oil does not; and white oil is a Group V product refined far beyond lubricant severity. Buy the product the application names, not the one that sits nearest to it on the refinery flowsheet.
Every base oil offer in the market is written against this classification. Groups I, II and III are defined by three measured properties and nothing else; Groups IV and V are defined by chemistry.
| Group | Saturates, % by mass (ASTM D2007) | Sulphur, % by mass (ASTM D2622 / D4294) | Viscosity index, dimensionless (ASTM D2270) | Usual production route |
|---|---|---|---|---|
| Group I | under 90 % | over 0.03 % | 80 to under 120 | Solvent extraction plus solvent dewaxing |
| Group II | 90 % or more | 0.03 % or less | 80 to under 120 | Hydrocracking with catalytic dewaxing |
| Group III | 90 % or more | 0.03 % or less | 120 or more | Severe hydrocracking or wax isomerisation; also gas-to-liquid |
| Group IV | not applicable | not applicable | not applicable | Polyalphaolefin (PAO), synthesised from decene |
| Group V | not applicable | not applicable | not applicable | Everything outside Groups I–IV: esters, polyalkylene glycols, naphthenics, alkylated naphthalenes, white oils |
The groups are a technical classification, but the reason a buyer cares about them is commercial. They decide who can use the oil, what it can be blended into, and how the price behaves.
API 1509 did not create the groups to rank quality. It created them to govern base oil interchange — the rules under which an engine oil licensed on one base stock can be reblended on another without repeating the full engine test programme. Substituting one Group I stock for another Group I stock of similar viscosity is a limited exercise. Crossing a group boundary triggers a far heavier read-across and retest burden. That administrative fact is the reason the group number appears on every base oil offer and inside every blender's purchasing specification.
Two pressures moved the market. The first is engine oil specification. Modern passenger-car oils are thin — SAE 5W-30, 0W-20 and lighter — and they are held to tight limits on evaporative loss; ILSAC GF-6 caps Noack volatility of the finished oil at 15 percent by mass. A Group I light neutral struggles to get there, because the same broad boiling range that comes with its aromatic and wax content also gives it a high volatile fraction. The second pressure is sulphur. Exhaust aftertreatment systems are poisoned by sulphur and phosphorus, so finished oil specifications cap sulphated ash, phosphorus and sulphur together. A Group I stock carrying several thousand parts per million of sulphur consumes much of that budget before a single additive is dosed.
The result has been a long sequence of Group I plant closures in Europe, North America and parts of Asia, with new Group II and Group III capacity built in the Middle East, Asia and North America. A buyer sees this in three ways: Group II availability has improved and its premium over Group I has narrowed; bright stock has become structurally scarce because only Group I plants make it; and heavy Group I neutrals have generally held value better than light ones.
Group I is not obsolete, and treating it as a legacy product is a mistake that costs formulators money. Its residual aromatic content gives it solvency, seen indirectly as a lower aniline point by ASTM D611 — a hydroprocessed stock of the same viscosity typically runs an aniline point some 10 to 20 °C higher. Solvency is what holds additives in solution during storage and holds oxidation by-products in solution during service instead of dropping them out as sludge. Group I also swells nitrile and other elastomer seals in a way severely hydroprocessed stocks do not, which matters in older equipment designed around it. Industrial and marine lubricants, greases, metalworking fluids, process and rubber oils and any formulation needing a genuinely heavy residual stock still call for Group I. Bright stock in particular has no like-for-like substitute.
Group III base oils are made from crude oil by severe hydroprocessing. Group IV polyalphaolefins are chemically synthesised from decene. A 1999 decision by the US National Advertising Division allowed Group III oils to be marketed as synthetic in the United States, and the convention spread from there. The practical consequence for a buyer is that the word on the label tells you very little; the group, the viscosity index and the Noack figure tell you what you are actually purchasing. Group V is the residual category and contains genuinely different chemistries — esters, polyalkylene glycols, alkylated naphthalenes, silicones, naphthenic oils and white oils — grouped together only because they fit nowhere else.
These are the four grades that carry most of the export trade in Group I base stock. Values below are the typical commercial specification quoted on Group I refinery data sheets, with the test method that produces each one.
| Property | Test method | SN 150 | SN 500 | SN 600 | BS 150 |
|---|---|---|---|---|---|
| Kinematic viscosity at 40 °C, cSt | ASTM D445 | 28–32 | 90–110 | 110–125 | 440–500 |
| Kinematic viscosity at 100 °C, cSt | ASTM D445 | 5.0–5.6 | 10.5–11.5 | 11.5–12.6 | 30–32 |
| Viscosity index, min | ASTM D2270 | 95 | 95 | 95 | 90 |
| Flash point, Cleveland open cup, °C, min | ASTM D92 | 200 | 230 | 240 | 280 |
| Pour point, °C, max | ASTM D97 | −9 | −6 | −6 | −6 |
| Colour, ASTM, max | ASTM D1500 | 1.5 | 3.0 | 3.5 | 8.0, run on the diluted sample |
| Total acid number, mg KOH/g, max | ASTM D664 | 0.05 | 0.05 | 0.05 | 0.10 |
| Density at 15 °C, g/cm³ | ASTM D4052 | 0.860–0.880 | 0.880–0.900 | 0.885–0.905 | 0.895–0.920 |
| Nearest ISO 3448 viscosity grade | ISO 3448 | ISO VG 32 | ISO VG 100 | between VG 100 and VG 150 | ISO VG 460 |
Nine lines carry almost all the commercial information in a base oil certificate, and the grade name on the drum decodes into two of them. Work down the sheet in this order and the awkward questions ask themselves.
SN stands for solvent neutral, and the number is approximately the viscosity of the oil in Saybolt Universal Seconds at 100 °F (37.8 °C). Saybolt viscosity is a legacy unit, long superseded by kinematic viscosity in centistokes, but the naming convention survived into the trade because everyone already knew it. ASTM D2161 gives the conversion, and above about 75 SUS the relationship settles at 4.6324 SUS per centistoke. Work it through: 500 SUS divided by 4.6324 gives about 108 cSt at 100 °F, which is why SN 500 lands in the 90 to 110 cSt band when measured at the modern reference temperature of 40 °C, a couple of degrees warmer and therefore a little thinner.
Bright stock breaks the pattern, and this is the single most common misreading in base oil enquiries. BS 150 is graded at 210 °F (98.9 °C), not at 100 °F. Run the same arithmetic at the higher reference temperature and 150 SUS gives roughly 32 cSt at 210 °F, which is why BS 150 shows 30 to 32 cSt at 100 °C and 440 to 500 cSt at 40 °C. It is roughly fifteen times thicker than SN 150 despite sharing the number. If an offer quotes a bright stock viscosity at 40 °C only, convert it before comparing.
ASTM D445 measures the time a fixed volume of oil takes to flow through a calibrated glass capillary under gravity, at a controlled temperature. The method reports in mm²/s; the trade almost always writes cSt. They are the same unit and the same number, so a certificate that says 98.4 mm²/s and an offer that says 98.4 cSt do not differ. It is the defining property of the grade, and it must be reported at both 40 °C and 100 °C. One temperature alone is not enough, because the pair is what tells you how the oil behaves across its working range and because the pair is the only input to viscosity index.
ASTM D2270 does not measure anything. It calculates a dimensionless number from the two kinematic viscosities, expressing how little viscosity is lost as the oil is heated. A high VI oil thins less. Group I solvent neutrals typically run 95 to 105, Group II 100 to 120, Group III 120 and above. Because VI is derived, a certificate that reports a viscosity index without reporting both kinematic viscosities is reporting an unsupported figure — ask for the inputs.
ASTM D92, the Cleveland open cup, gives the temperature at which vapour above the heated oil first flashes with an applied flame. For base oil it does two jobs. It sets the safe ceiling for blending and storage temperature, and it is a sensitive detector of contamination: a heavy neutral that should flash above 230 °C but comes in at 180 °C has light ends in it, and the most likely explanation is a dirty tank, a dirty drum or a deliberate cut. Do not accept a closed-cup result (ASTM D93) in place of an open-cup one without adjusting expectations; the two methods do not give the same number.
ASTM D97 cools the sample in 3 °C steps and records the lowest temperature at which it still moves. For a solvent-dewaxed Group I stock the pour point is set by how much wax the dewaxing unit removed, and it governs whether a tank or a line will still pump on a cold morning. Bright stock and heavy neutrals can show pour point reversion: an oil that passed at −6 °C when fresh can gel at a higher temperature after weeks of slow cooling in storage, because wax crystals continue to grow. Storage design should allow headroom below the certified figure rather than treating it as an operating limit.
ASTM D1500 compares the sample against calibrated glass standards on a 0.5 to 8.0 scale. It is not a performance property, but it is the cheapest and fastest integrity check available: colour reflects refining severity, and a batch that arrives darker than its certificate is either not the batch tested, has been stored hot, or has picked something up. For water-white Group II and Group III stocks D1500 loses resolution and the Saybolt colour scale (ASTM D156) is used instead.
ASTM D664 titrates the sample potentiometrically and reports the milligrams of potassium hydroxide needed to neutralise one gram of oil. A fresh base stock should be essentially neutral, typically 0.05 mg KOH/g or below. An elevated TAN on a supposedly virgin stock means oxidation, and the most common reason for oxidation in a base oil that has never been used is that some of it has been used.
ASTM D4052 measures density in an oscillating U-tube at a controlled temperature, normally reported at 15 °C. Traders need it because base oil is sold by mass and shipped in volume: one tonne of SN 500 at 0.885 g/cm³ occupies about 1,130 litres at 15 °C. Volumes measured at any other temperature must be corrected back to the reference temperature using ASTM D1250 (API MPMS Chapter 11.1) before quantities are compared, and a five-degree tank temperature difference is worth roughly 0.35 percent of volume. Agree in the contract whether quantity is determined by weight or by corrected volume; disputes here are arithmetic, not chemistry, and they are entirely avoidable.
ASTM D5800 holds the sample at 250 °C for one hour with air drawn across it at a fixed slight vacuum, and reports the mass lost as a percentage. It predicts how much oil will evaporate out of a hot engine, and it is the property that most sharply separates the groups at a given viscosity. For a blender making automotive oils it is a pass-or-fail input. For an industrial oil blender it matters much less, and there is no point paying for a low-Noack stock to make a gear oil.
Base oil is a favourite target for extension, because heavy aromatic extract and re-refined or used oil can be blended into it without changing the viscosity much. Four inexpensive tests catch nearly all of it. Sulphated ash (ASTM D874) should be nil on a virgin base stock, because base oil contains no metallic additives. Elemental analysis by ASTM D5185 should show calcium, zinc, phosphorus, magnesium and barium essentially absent; any meaningful reading of those elements indicates additive-containing oil in the tank. Water content by ASTM D6304 catches wet stock. And colour plus TAN together catch aged material. Ask for these four on the COA for any new supplier, and specify that they be run at load port rather than at destination.
The property list a complete base oil certificate should carry, with the primary standard, the recognised alternative, an indicative value for SN 500 and the reason the line is on the sheet.
| Property | Primary method | Alternative or ISO equivalent | Indicative value, SN 500 | What it controls |
|---|---|---|---|---|
| Kinematic viscosity at 40 °C | ASTM D445 | ISO 3104 | 90–110 cSt | Grade identity and the ISO 3448 band the finished blend lands in |
| Kinematic viscosity at 100 °C | ASTM D445 | ISO 3104 | 10.5–11.5 cSt | High-temperature film thickness; second input to viscosity index |
| Viscosity index | ASTM D2270 | ISO 2909 | min 95 | How much viscosity is lost between 40 and 100 °C |
| Flash point, Cleveland open cup | ASTM D92 | ISO 2592 | min 230 °C | Blending and storage temperature ceiling; detects light-ends contamination |
| Pour point | ASTM D97 | ISO 3016 | max −6 °C | Lowest temperature at which the oil still moves in a tank or line |
| Colour | ASTM D1500 | ISO 2049 / ASTM D156 | max 3.0 | Refining severity and freshness; fastest contamination check |
| Total acid number | ASTM D664 | ASTM D974 | max 0.05 mg KOH/g | Oxidation state; elevated TAN points to aged or used stock |
| Density at 15 °C | ASTM D4052 | ASTM D1298 / ISO 12185 | 0.880–0.900 g/cm³ | Mass to volume conversion for invoicing and tank gauging |
| Noack volatility, 250 °C, 1 h | ASTM D5800 | CEC L-40-A-93 | under 5 % m/m | Evaporative loss in service; decisive for engine oil blending |
| Sulphur | ASTM D4294 | ASTM D2622 | typically 0.3–1.0 % m/m | API 1509 group assignment; aftertreatment compatibility |
| Saturates | ASTM D2007 | ASTM D6074 (guide) | typically 60–85 % for Group I | API 1509 group assignment; oxidation stability |
| Aniline point | ASTM D611 | ISO 2977 | typically 95–110 °C for Group I | Solvency for additives and seal-swell behaviour |
| Water content | ASTM D6304 | ASTM D95 | nil by D95; below 200 mg/kg by Karl Fischer | Hazing, foaming and boil-over risk in heated tanks |
| Carbon residue, Conradson | ASTM D189 | ASTM D524 (Ramsbottom) | under 0.1 % m/m | Residual heavy ends and deposit-forming tendency |
| Sulphated ash | ASTM D874 | ASTM D482 (oxide ash) | nil on virgin stock | Detects additive-containing or used-oil contamination |
| Additive and wear elements | ASTM D5185 | not applicable | Ca, Zn, P essentially absent | The most direct test for used-oil blending |
Grade selection in blending is mostly viscosity arithmetic: the blender picks two or three stocks that bracket the target and mixes to the ISO or SAE grade required.
The light neutral. Spindle and light hydraulic oils around ISO VG 32, light circulating oils, textile and light process oils, and the thinning component that pulls a heavy blend down onto grade. Its higher volatility limits its use in engine oils.
The workhorse of the trade and usually the most liquid grade in the market. Engine oil blending, ISO VG 68 and VG 100 industrial and hydraulic oils, general machine oils, cutting and quenching oil bases, and rust preventives.
Used where SN 500 is marginally too thin to reach the target without adding bright stock. Heavier industrial oils, monograde engine oils, gear oil blends and compressor oils. Commercially it tracks SN 500 closely.
The viscosity builder. Marine cylinder oils, ISO VG 320 to VG 680 industrial gear oils, greases, tackifying and adhesive compounds, cable and metal-forming oils. Small percentages move a blend a long way.
Base oil viscosity, not thickener content, sets the temperature and speed range of a finished grease. Lithium and calcium soap greases typically use an SN 500 and bright stock blend to reach the base oil viscosity the NLGI grade requires.
Solvent neutrals also serve as carrier fluids in metalworking concentrates, mould release, chain and conveyor oils, and as diluents in industrial formulations where a light-coloured, low-acid, low-volatility hydrocarbon is required.
Base oil is combustible rather than flammable and is not acutely toxic, which makes it easy to be careless with. The three incidents that actually happen are hot-oil burns, water flashing in a heated tank, and long-term skin exposure.
With a Cleveland open cup flash point of 200 to 280 °C depending on grade, base oil will not ignite from a spark at ambient temperature. The risk appears when it is heated. Blending kettles, drum-heating rooms and steam-traced lines can all put oil above its flash point, and a leak onto hot lagging is a classic ignition path because lagging holds oil in a large surface area at high temperature. Keep bulk and drum storage well below the flash point, log the temperature of any heated tank, and repair lagging leaks rather than wiping them. For an oil fire use foam, dry chemical or carbon dioxide. Never direct a water jet at burning oil — it spreads the fire and can cause a violent eruption.
Free water at the bottom of a base oil tank is the most under-rated risk in a blending plant. If the tank is heated above 100 °C, that water flashes to steam and expands by a factor of roughly 1,600, throwing hot oil out of the hatch. The same mechanism causes foaming and boil-over in a kettle. Drain tank low points before applying heat, check water by ASTM D95 or ASTM D6304 on receipt, and never apply heat to a drum or tank whose water content is unknown. Water also causes hazing and accelerates additive drop-out downstream, so the operational and quality arguments point the same way.
The health profile of a base oil depends entirely on how severely it was refined. Untreated and mildly treated mineral oils are classified by IARC in Group 1 — carcinogenic to humans — while highly refined mineral oils sit in Group 3. The industry test that separates the two is IP 346, which measures polycyclic aromatic content as dimethyl sulphoxide extractables; a result below 3 percent is the threshold at which a mineral oil is not classified as carcinogenic under the EU regime. Ask for the IP 346 result for any base oil that will be in contact with people, and treat its absence from a data sheet as a question to raise rather than a formality.
For airborne exposure, the ACGIH threshold limit value for mineral oil mist, excluding metalworking fluids, is 5 mg/m³ as an eight-hour time-weighted average of the inhalable fraction. Mist and aerosol are generated by splash filling, by compressed-air blow-down and by high-speed machining, so control those operations rather than relying on general ventilation.
Skin contact is the routine exposure route. Repeated or prolonged contact defats the skin and causes dermatitis, and contact through saturated clothing causes oil folliculitis. Nitrile gloves, eye protection when transferring, prompt change of oil-soaked clothing, and washing with soap and water are the whole control set. Never use solvent, and never use compressed air, to clean oil off skin.
Store drums indoors and, if that is impossible, on their sides with both bungs at the three and nine o'clock positions so the closures stay below any standing water. Drums breathe: as ambient temperature cycles day to night the headspace expands and contracts, and an upright drum with water pooled on its head will draw that water past the bung seal. Water ingress is the single largest cause of rejected base oil at destination and it is entirely preventable by how the drums are laid down.
Keep base oil away from strong oxidising agents. Sealed and stored under cover, a plain base stock remains serviceable for a long period because it has no additives to separate or degrade; the practical limits are water ingress and drum corrosion rather than the oil itself. Once a drum is opened, close it properly, because an open bung is an open water path.
Treat any spill as an oil spill: stop the source, contain, absorb with inert material such as sand or commercial absorbent, and dispose through a licensed waste oil route. Do not flush base oil to a drain or a watercourse. Spilled oil on a plant floor is also a serious slip hazard and should be cleaned before it is documented. Every shipment should travel with a GHS-format Safety Data Sheet, the Technical Data Sheet and the batch Certificate of Analysis, and many destination customs authorities now ask for the SDS at clearance.
For base oil the packing decision is really a contamination decision. Every transfer between vessel, drum, tote and blend tank is another chance to pick up water, rust or the residue of whatever was in the container last — and colour, total acid number and water content are precisely the lines that fail on arrival when it goes wrong. Cost per tonne follows from that, not the other way round.
| Packing | Nominal capacity | Typical net weight | Per 20 ft container | Best suited to |
|---|---|---|---|---|
| New steel drum | 200–210 L | approx. 180 kg | 80 drums, about 14.4 MT | Blenders without bulk receipt; mixed-grade and mid-size lots |
| IBC / tote | 1,000 L | approx. 880 kg | 10 IBCs, about 8.8 MT | Trial quantities, speciality grades and small formulators |
| Flexitank in a 20 ft container | 20,000–24,000 L | about 17.5–21 MT | 1 flexitank | Single-grade parcels; no drum disposal at destination |
| ISO tank container | 21,000–26,000 L | about 18–23 MT | 1 tank | Buyers with pump-off capability and dedicated tank storage |
| Bulk vessel parcel | parcel size | 1,000 MT and above | not applicable | Terminals and large blending plants with shore tankage |
It is the main component of almost every finished lubricant. A passenger-car engine oil is roughly 75 to 85 percent base oil by mass, a straight mineral hydraulic oil can be 98 to 99 percent, and greases are base oil plus a thickener and additives. It is also used as a carrier fluid in metalworking concentrates, mould release, chain oils and industrial formulations. It is not a finished lubricant on its own and must not be used as one.
The difference is three measured numbers under API 1509. Group I has under 90 percent saturates or over 0.03 percent sulphur, with viscosity index from 80 to under 120. Group II has at least 90 percent saturates and no more than 0.03 percent sulphur, with the same viscosity index band. Group III meets the Group II purity limits but has a viscosity index of 120 or above. Group I comes from solvent refining; Groups II and III come from hydroprocessing. Saturates are measured by ASTM D2007, sulphur by ASTM D2622 or D4294 and viscosity index calculated by ASTM D2270.
SN stands for solvent neutral and 500 is approximately the viscosity in Saybolt Universal Seconds at 100 degrees Fahrenheit, a legacy unit retained by the trade. Converting with ASTM D2161 at 4.6324 SUS per centistoke gives about 108 cSt at 100 °F, which is why SN 500 typically measures 90 to 110 cSt at 40 °C by ASTM D445 and around 10.5 to 11.5 cSt at 100 °C.
Because they are graded at different reference temperatures. Solvent neutral numbers are Saybolt seconds at 100 °F, but bright stock numbers are Saybolt seconds at 210 °F. BS 150 therefore means about 30 to 32 cSt at 100 °C, which corresponds to roughly 440 to 500 cSt at 40 °C — about fifteen times the viscosity of SN 150. Bright stock is also a residual product made from deasphalted vacuum residue rather than a distillate cut.
They overlap but they are not the same statement. ISO 3448 defines VG 100 as a kinematic viscosity of 90 to 110 cSt at 40 °C, and a typical SN 500 falls inside that band, so an SN 500 will usually satisfy an ISO VG 100 viscosity requirement. ISO VG is a viscosity band only; SN 500 additionally implies a Group I solvent-refined origin with its associated sulphur, colour and aniline point. Where a specification names an ISO VG grade, check whether it also names a base stock group.
Not without qualification. Group II has higher purity, higher viscosity index, lighter colour and lower volatility, but it also has lower solvency, seen as a higher aniline point under ASTM D611, and it swells elastomer seals less. Additives that stayed in solution in a Group I stock may drop out in a Group II one. In licensed engine oils, crossing a group boundary also triggers the API 1509 base oil interchange retest requirements. Bench-test the reformulation and, for licensed products, check the interchange rules before you commit.
Divide 1,000 by the density in kg per litre at 15 °C. At 0.885 kg/L, typical for SN 500, one tonne is about 1,130 litres. A lighter SN 150 at 0.870 gives about 1,150 litres and a bright stock at 0.905 about 1,105 litres. Volumes measured at any other temperature must be corrected to 15 °C using ASTM D1250 before they are compared; roughly 0.35 percent of volume moves per five degrees of temperature difference.
Ask for four tests on the batch certificate. Sulphated ash by ASTM D874 should be nil, because virgin base oil contains no metallic additives. Elemental analysis by ASTM D5185 should show calcium, zinc, phosphorus, magnesium and barium essentially absent. Total acid number by ASTM D664 should be at or below about 0.05 mg KOH/g. Colour by ASTM D1500 should match the grade. Specify that these are run on a sample drawn at load port under independent supervision, with sealed retained samples held by both parties.
Send the grade (SN 150, SN 500, SN 600 or BS 150), quantity, packing, destination port and Incoterm. If you blend to a fixed internal specification, attach it — the offer will be checked line by line against it, and anything that cannot be met will be stated before pricing rather than left for the Certificate of Analysis to reveal later. Enquiries are handled on WhatsApp at +971 56 144 5733.