Most buyers who search for group II base oil 80N, 100N or 400N are not looking for a chemistry lecture. They are looking for numbers: what viscosity does this grade actually run at, what flash point should the certificate show, and which finished lubricant does it belong in. So this guide leads with the table. If you want the broader explanation of what the API groups are and why Group II matters at all, read the companion article, Group II+ base oils explained — that one covers the what and the why. This one covers the grades and the numbers.
One caveat before the table, and it matters commercially. The figures below are typical industry ranges for hydrocracked Group II neutral stocks. They are not a batch certificate. Refinery slates differ, and every parcel ships against its own certificate of analysis. Use these ranges to specify and to sanity-check an offer; blend and formulate against the actual COA and TDS for the lot you are buying.
Group II base oil specifications by grade
| Grade | KV at 40°C (cSt) | KV at 100°C (cSt) | Viscosity index | Flash point, COC (°C) | Pour point (°C) | Sulphur (% m/m) | Saturates (% m/m) | Typical use |
|---|---|---|---|---|---|---|---|---|
| 70N | 12 – 14 | 3.0 – 3.3 | 95 – 105 | 190 – 210 | -18 to -12 | < 0.03 | > 99 | Spindle oils, light hydraulics, process and white-oil feed |
| 80N | 14 – 17 | 3.4 – 3.8 | 95 – 105 | 200 – 215 | -18 to -12 | < 0.03 | > 99 | Light hydraulic fluids, ATF and light engine-oil blends |
| 100N | 19 – 22 | 4.0 – 4.4 | 100 – 110 | 210 – 225 | -18 to -12 | < 0.03 | > 99 | Hydraulic ISO VG 32/46, passenger-car light multigrades |
| 150N | 28 – 33 | 5.1 – 5.6 | 100 – 110 | 220 – 235 | -15 to -9 | < 0.03 | > 99 | The workhorse light stock in 15W-40 and VG 46/68 blends |
| 220N | 40 – 47 | 6.3 – 6.9 | 100 – 110 | 230 – 245 | -15 to -9 | < 0.03 | > 99 | Mid-grade engine oils, VG 68/100 industrial oils |
| 300N | 58 – 68 | 7.8 – 8.6 | 100 – 108 | 235 – 250 | -15 to -9 | < 0.03 | > 99 | Bridging stock for gear oils and heavier hydraulics |
| 400N | 78 – 90 | 9.4 – 10.3 | 98 – 108 | 240 – 255 | -12 to -9 | < 0.03 | > 99 | Industrial gear oils, grease base fluid, VG 100/150 |
| 500N | 95 – 112 | 10.8 – 11.8 | 95 – 105 | 245 – 260 | -12 to -9 | < 0.03 | > 99 | Heavy-duty diesel multigrades, VG 150/220 |
| 600N | 115 – 135 | 12.0 – 13.2 | 95 – 105 | 250 – 270 | -12 to -6 | < 0.03 | > 99 | Heavy gear oils, monogrades, grease and VG 220/320 |
| Brightstock (BS 150) | 400 – 500 | 28 – 32 | 90 – 98 | 290 – 315 | -9 to 0 | 0.5 – 1.0 | 60 – 75 | Very high-viscosity blends, open gear, marine, grease |
Read the brightstock row carefully, because it answers a question that comes up constantly in Group I and Group II brightstock enquiries. Brightstock is a residual stock, not a distillate neutral. Nearly all commercial brightstock is Group I: its sulphur sits well above the 0.03% limit and its saturates fall below 90%, so by definition it is not a Group II product. Group II brightstock does exist but supply is limited and priced accordingly. In practice a blender building a very heavy oil will pair Group II neutrals with a Group I brightstock and accept the small step down in purity for the viscosity and solvency it delivers.
What the N actually means in 80N, 150N and 600N
The N stands for neutral, a term carried over from solvent-neutral refining, where the finished stock was neutral in acidity after treatment. The number is the approximate viscosity of the oil in Saybolt Universal Seconds (SUS) at 100°F — the imperial measurement standard that predates the metric kinematic viscosity at 40°C used on every data sheet today.
The arithmetic still holds, which is why the table above lines up so neatly. Roughly 100 SUS converts to about 20.6 cSt, so a 100N reads around 20 cSt at 40°C. A 500N converts to about 108 cSt, and a 220N to about 47 cSt. Once you know the conversion, an unfamiliar grade designation stops being a mystery: multiply the N number by roughly 0.216 and you have the approximate cSt at 40°C.
Two practical warnings follow from this. First, the N number is a commercial label, not a measured specification. One refiner's 220N may certify at 41 cSt and another's at 46 cSt, and both are legitimately sold as 220N. Second, prefixes matter in trade documents: SN150 usually signals a Group I solvent-neutral stock, while 150N or N150 more often signals a hydrocracked Group II. The two are not interchangeable in an additive-sensitive formulation, so confirm the group in writing before you contract.
Where Group II sits: the API base oil classification
| API group | Saturates (% m/m) | Sulphur (% m/m) | Viscosity index | Typical process |
|---|---|---|---|---|
| Group I | < 90 | > 0.03 | 80 – 120 | Solvent refining and dewaxing |
| Group II | ≥ 90 | ≤ 0.03 | 80 – 120 | Hydrocracking, hydrofinishing |
| Group II+ | ≥ 90 | ≤ 0.03 | ~110 – 120 | Deeper hydroprocessing (commercial sub-grade) |
| Group III | ≥ 90 | ≤ 0.03 | > 120 | Severe hydrocracking / catalytic dewaxing |
The three test values in that table — saturates, sulphur and viscosity index — are the entire definition. Every grade in the first table, from 70N to 600N, is Group II because it clears the same three limits; the N number only tells you how thick it is. Note also that Group II+ is not an official API category. It is a widely used commercial designation for Group II stocks whose viscosity index lands at the top of the band, and it is the tier Axabull refines its finished lubricants from.
Matching the grade to the finished lubricant
| Base oil grade | Blends into | Why this grade |
|---|---|---|
| 70N – 100N | Light hydraulic oils (ISO VG 32/46), light passenger-car multigrades, ATF, compressor oils | Low viscosity and low pour point give cold-start flow and pumpability |
| 150N – 220N | Mainstream 15W-40 and 20W-40 engine oils, ISO VG 46/68 hydraulic and circulating oils, light gear oils | The best balance of film strength and flow; the most traded grades globally |
| 300N – 400N | Industrial gear oils (VG 100/150), grease base fluid, heavier hydraulics | Higher flash point and load-carrying film without excessive drag |
| 500N – 600N | Heavy-duty diesel multigrades, monogrades, VG 220/320 gear oils, greases | Provides the high-temperature viscosity backbone of the blend |
| Brightstock | Very high-viscosity gear and open-gear oils, marine cylinder oils, tacky greases | Extreme viscosity and solvency that distillate neutrals cannot reach |
Blenders rarely use a single grade
A finished lubricant is almost never one neutral straight from the tank. A blender selects a light stock and a heavy stock and combines them to land on a target viscosity at 100°C, a target viscosity index and a target volatility, before the additive package goes in. A typical 15W-40 heavy-duty diesel oil, for example, is commonly built on a 150N and a 500N or 600N, with a viscosity index improver and a detergent-inhibitor package on top. An ISO VG 46 hydraulic oil might sit almost entirely on 150N with a small heavy correction.
The N grade sets the physics of the blend. The additive package sets its job. Get the base oil selection wrong and no additive treat rate will rescue the finished product.
What to check on the certificate of analysis
- Kinematic viscosity at both 40°C and 100°C (ASTM D445) — one value alone hides the viscosity index.
- Viscosity index (ASTM D2270) — the single best indicator of whether you have been offered Group II, Group II+ or a Group I stock relabelled.
- Flash point, Cleveland open cup (ASTM D92) — a low result for the grade suggests light-end contamination.
- Pour point (ASTM D97) — decides low-temperature handling and storage in cooler markets.
- Sulphur (ASTM D4294 or D2622) and saturates (ASTM D2007) — the two values that prove the Group II claim.
- Colour (ASTM D1500) and Noack volatility (ASTM D5800) where the finished product has appearance or oil-consumption targets.
If a supplier cannot produce viscosity index, sulphur and saturates on the same document, you do not yet have a verified Group II offer — you have a viscosity grade and a description.
From base oil grade to finished product
Axabull Industries Pvt. Ltd., founded in 2013 and headquartered in Surat, Gujarat, refines its lubricants from imported Group II+ base oils across exactly this range of neutral grades. The lighter stocks go into hydraulic oils and light automotive multigrades; the mid grades carry the volume automotive engine oil range for bikes, cars, trucks, tractors and CNG vehicles; the heavier neutrals underpin industrial gear oils, greases and the wider industrial fluids catalogue.
For distributors and importers, the practical value of understanding grades is leverage. When you can read a data sheet and know that a 15W-40 built on Group II+ neutrals will behave differently in a hot-climate fleet than one built on Group I, you buy on substance rather than on label. That is the conversation Axabull prefers to have with its partners across a pan-India network of 5,000-plus retailers, five depots and 16 export markets.
If you are specifying finished lubricants for a market, a fleet or a private-label programme and want to talk grades, viscosity targets and pack formats, start with the global B2B and export page or contact the Axabull team with your application and volumes. We will come back with the technical data sheets for the products that fit.