Oil Viscosity Quick Reference — ISO VG to SAE
Industrial oils use ISO VG ratings (per ISO 3448); engine and gear oils use SAE ratings. The ISO VG number equals the kinematic viscosity in centistokes (cSt) at 40°C operating temperature, ±10%.
| ISO VG | cSt at 40°C | ≈ SAE Crankcase | ≈ SAE Gear | Common Industrial Use |
|---|---|---|---|---|
| VG 22 | 19.8–24.2 | 5W | 75W | Light hydraulic, cold-climate circulating |
| VG 32 | 28.8–35.2 | 10W | 75W | Standard hydraulics, light circulating oils |
| VG 46 | 41.4–50.6 | 15W | 80W | General-purpose hydraulics, most workshops |
| VG 68 | 61.2–74.8 | 20W | 80W | Bearings, general industrial circulating |
| VG 100 | 90–110 | 30 | 85W | Heavy-duty bearings, air compressors |
| VG 150 | 135–165 | 40 | 90 | Industrial gearboxes |
| VG 220 | 198–242 | 50 | 90 | Heavy gearboxes, worm drives |
| VG 320 | 288–352 | 60 | 140 | High-load gearboxes, slow-speed bearings |
| VG 460 | 414–506 | — | 140 | Heavy industrial gear oil |
What Viscosity Is — and Why the Number Matters
Viscosity is a fluid's resistance to flow. A high-viscosity oil flows slowly and maintains a thick film between moving surfaces; a low-viscosity oil flows freely but provides less protection under heavy loads and high temperatures. In industrial and maintenance applications, selecting the wrong viscosity is one of the most common causes of premature equipment wear — and it is entirely preventable with the right reference.
For applications where ISO VG / SAE viscosity grading doesn't apply — dry-film lubrication on plastics, rails, hinges and food-grade equipment — PTFE aerosol is the standard alternative. See the Teflon (PTFE) spray guide for dry-film selection.
This article is a cross-system reference tool. It explains the ISO VG grading system, provides the full 20-grade viscosity chart, and gives the conversion tables between ISO VG, SAE engine oil, SAE gear oil, and AGMA grades that maintenance engineers and tradespeople look up constantly. For detailed selection guidance by application, see the linked specialist guides below each table.
The ISO VG System: What the Number Represents
ISO VG stands for International Organisation for Standardisation Viscosity Grade. The system was established in 1975 through collaboration between the ISO, ASTM, STLE, BSI, and DIN — the result was a single universal classification that replaced a patchwork of national and industry-specific grading systems.
The ISO VG number represents the oil's nominal kinematic viscosity in centistokes (cSt) measured at 40°C. The standard (ISO 3448, 1992) allows a tolerance of ±10% around that nominal value. So ISO VG 46 oil must have a viscosity between 41.4 cSt and 50.6 cSt at 40°C.
There are 20 ISO VG grades in the standard, from VG 2 to VG 3200. Each successive grade is approximately 50% higher in viscosity than the previous one — the scale is roughly logarithmic. The system covers everything from very light instrument oils at the bottom end to heavy open gear compounds at the top.
What ISO VG does not tell you: the additive package, base oil type, or how the oil behaves at temperatures other than 40°C. An ISO VG 68 hydraulic oil and an ISO VG 68 gear oil have the same viscosity at 40°C but are entirely different products formulated for different applications. Never substitute one for the other based on ISO VG number alone.
Full ISO VG Viscosity Chart — All 20 Grades
The table below covers all 20 ISO VG grades defined in ISO 3448. Kinematic viscosity ranges are the nominal ±10% tolerance limits at 40°C.
| ISO VG Grade | Nominal Viscosity at 40°C (cSt) | Minimum (cSt) | Maximum (cSt) | Typical Applications |
|---|---|---|---|---|
| ISO VG 2 | 2.2 | 1.98 | 2.42 | Instrument oils, precision spindles |
| ISO VG 3 | 3.2 | 2.88 | 3.52 | Precision instrument oils |
| ISO VG 5 | 4.6 | 4.14 | 5.06 | Light instrument and spindle oils |
| ISO VG 7 | 6.8 | 6.12 | 7.48 | Spindle oils, high-speed bearings |
| ISO VG 10 | 10 | 9.00 | 11.0 | Spindle oils, pneumatic tool oil |
| ISO VG 15 | 15 | 13.5 | 16.5 | Hydraulic jack oil, airline lubricators |
| ISO VG 22 | 22 | 19.8 | 24.2 | Air compressors, light hydraulic systems, turbine oils |
| ISO VG 32 | 32 | 28.8 | 35.2 | Hydraulic systems (cold climates), machine tools, circulating systems |
| ISO VG 46 | 46 | 41.4 | 50.6 | General industrial hydraulics, mobile plant, most Australian conditions |
| ISO VG 68 | 68 | 61.2 | 74.8 | High-temperature hydraulics, light gear oil, circulating systems |
| ISO VG 100 | 100 | 90.0 | 110 | Medium gearboxes, circulating systems, some compressors |
| ISO VG 150 | 150 | 135 | 165 | Industrial gearboxes, heavy circulating systems |
| ISO VG 220 | 220 | 198 | 242 | Industrial gearboxes, enclosed gear drives, worm gears |
| ISO VG 320 | 320 | 288 | 352 | Heavy industrial gearboxes, large enclosed gear drives |
| ISO VG 460 | 460 | 414 | 506 | Very heavy gearboxes, slow-speed high-load applications |
| ISO VG 680 | 680 | 612 | 748 | Heavy open gears, very slow gearboxes, some worm drives |
| ISO VG 1000 | 1000 | 900 | 1100 | Open gear compounds, very heavy slow equipment |
| ISO VG 1500 | 1500 | 1350 | 1650 | Open gear compounds, high-load slow-moving equipment |
| ISO VG 2200 | 2200 | 1980 | 2420 | Heavy open gear compounds |
| ISO VG 3200 | 3200 | 2880 | 3520 | Heaviest open gear compounds, specialised low-speed industrial applications |
Source: ISO 3448:1992 Industrial liquid lubricants — ISO viscosity classification.
ISO VG to SAE Engine Oil Conversion Chart
SAE engine oil grades (such as SAE 30, SAE 10W-30) are defined by the Society of Automotive Engineers and are measured at different temperatures and under different test conditions than ISO VG. The conversion table below shows approximate viscosity equivalents at 40°C — it is a reference guide only. SAE engine oil and ISO VG industrial oil are not interchangeable. Even if two oils show the same viscosity number, their additive packages are completely different: engine oils contain detergents, dispersants, and friction modifiers that have no place in hydraulic, gear, or compressor systems.
Use this table to understand what a viscosity number means in a different grading system — not as a substitution guide.
| ISO VG Grade | Approximate SAE Engine Grade Equivalent | Viscosity at 40°C (cSt) |
|---|---|---|
| ISO VG 15 | SAE 5W | ~15 cSt |
| ISO VG 22 | SAE 5W–10W | ~22 cSt |
| ISO VG 32 | SAE 10W | ~32 cSt |
| ISO VG 46 | SAE 15W | ~46 cSt |
| ISO VG 68 | SAE 20W / SAE 20 | ~68 cSt |
| ISO VG 100 | SAE 30 | ~100 cSt |
| ISO VG 150 | SAE 40 | ~150 cSt |
| ISO VG 220 | SAE 50 | ~220 cSt |
| ISO VG 320 | SAE 60 | ~320 cSt |
Approximate equivalents only. Do not use engine oil in place of ISO VG industrial oil or vice versa.
ISO VG to SAE Gear Oil Conversion Chart
SAE gear oil grades (SAE 75W, 80W, 90, 140) are a separate viscosity classification from SAE engine grades — they use the same numbering prefix but represent different viscosity ranges. SAE gear oil grades are measured at 100°C (high-temperature test) and at low temperature, whereas ISO VG is measured at 40°C. The table below shows approximate equivalents.
| ISO VG Grade | Approximate SAE Gear Grade Equivalent | Typical Applications |
|---|---|---|
| ISO VG 46 | SAE 75W | Light gear applications, some axles |
| ISO VG 68 | SAE 80W | Light industrial gearboxes |
| ISO VG 100 | SAE 80W–90 | Medium gearboxes |
| ISO VG 150 | SAE 90 | Industrial gearboxes, differentials |
| ISO VG 220 | SAE 90–140 | Enclosed industrial gear drives |
| ISO VG 320 | SAE 140 | Heavy industrial gearboxes |
| ISO VG 460 | SAE 140–250 | Very heavy gearboxes, slow worm drives |
| ISO VG 680 | SAE 250 | Heavy worm gearboxes, slow-speed high-load |
Approximate equivalents only. SAE gear oil and ISO VG gear oil are not universally interchangeable — additive packages and EP ratings differ significantly. Always check OEM specification.
ISO VG to AGMA Conversion Chart
The American Gear Manufacturers Association (AGMA) viscosity system is used widely for industrial gearboxes, particularly in US-designed equipment common in Australian mining, food processing, and heavy industry. AGMA grades run from AGMA 0 (lightest) to AGMA 13 (heaviest). The table below shows the ISO VG equivalents used in Australian and international industrial practice.
| AGMA Grade | ISO VG Equivalent | Viscosity Range at 40°C (cSt) |
|---|---|---|
| AGMA 0 | ISO VG 46 | 41.4–50.6 |
| AGMA 1 | ISO VG 68 | 61.2–74.8 |
| AGMA 2 | ISO VG 100 | 90–110 |
| AGMA 3 | ISO VG 150 | 135–165 |
| AGMA 4 | ISO VG 220 | 198–242 |
| AGMA 5 | ISO VG 320 | 288–352 |
| AGMA 6 | ISO VG 460 | 414–506 |
| AGMA 7 | ISO VG 680 | 612–748 |
| AGMA 8 | ISO VG 1000 | 900–1100 |
| AGMA 8A EP | ISO VG 1500 | 1350–1650 |
AGMA 250.04 standard. EP suffix indicates extreme pressure additive package — verify whether OEM specification requires EP grade before selecting.
ISO VG for Hydraulic Oil
Most hydraulic systems in Australian industry run on ISO VG 32, 46, or 68 mineral hydraulic oil. ISO VG 46 is the most common grade for general industrial and mobile applications in temperate Australian conditions — it balances cold-start flow, film protection, and operating temperature performance for the majority of workshop presses, mobile plant, agricultural machinery, and industrial hydraulic units.
| ISO VG Grade | Typical Hydraulic Application | Ambient Temperature Range |
|---|---|---|
| ISO VG 22 | Light hydraulic circuits, jack oil top-up in some equipment | Below 15°C ambient |
| ISO VG 32 | Machine tools, high-speed hydraulics, cold-climate equipment | 0°C to 35°C |
| ISO VG 46 | General industrial hydraulics, mobile plant, most Australian applications | 10°C to 50°C |
| ISO VG 68 | High-temperature systems, high-pressure equipment, older equipment with worn clearances | 20°C to 60°C |
| ISO VG 100 | Very high temperature industrial equipment, tropical environments | 30°C to 70°C |
For detailed hydraulic oil selection — AW vs HVI grades, zinc-based vs zinc-free, fluid types, change intervals, and contamination — see the AIMS Hydraulic Oil Guide.
Shop hydraulic oil: AIMS hydraulic oil range — ISO VG 32, 46, and 68 in 5L, 20L, and drum quantities.
ISO VG for Gear Oil
Industrial gearboxes use significantly heavier viscosity grades than hydraulic systems. The operating principle is different — gear teeth require a thick film that withstands extreme pressure contact (EP) at the tooth mesh — and the operating temperatures in enclosed gearboxes are typically higher than hydraulic reservoirs. Most enclosed industrial gearboxes in Australian maintenance environments run on ISO VG 150 to ISO VG 460.
| ISO VG Grade | Typical Gearbox Application | Notes |
|---|---|---|
| ISO VG 68 | Light industrial gearboxes, high-speed low-load units | Uncommon — check OEM spec |
| ISO VG 100 | Medium-speed gearboxes, some circulating systems | Often with EP additive |
| ISO VG 150 | General industrial gearboxes, moderate speed and load | EP grade usually required |
| ISO VG 220 | Most common general-purpose industrial gearbox grade | EP grade standard |
| ISO VG 320 | Heavy industrial gearboxes, higher load applications | EP grade standard |
| ISO VG 460 | Heavy slow gearboxes, large reducers | EP grade standard |
| ISO VG 680 | Very slow heavy gearboxes, worm drives | Specialist; check OEM spec |
For detailed gear oil selection — EP ratings, synthetic vs mineral, AGMA grades, change intervals, and worm gear requirements — see the AIMS Gear Oil Guide.
ISO VG for Compressor Oil
Compressor oil viscosity requirements differ by compressor type. Reciprocating compressors typically require heavier oil (ISO VG 100–150) that can withstand the high temperatures at cylinder walls. Rotary screw compressors — the most common type in Australian industrial workshops — use lighter synthetic or semi-synthetic oils typically in the ISO VG 46–68 range, often specified as a proprietary compressor fluid rather than a standard industrial oil. Vane compressors commonly run on ISO VG 46–68 mineral oil.
| Compressor Type | Typical ISO VG Grade | Notes |
|---|---|---|
| Rotary screw (air-cooled) | ISO VG 46–68 (synthetic or semi-synthetic) | Many OEMs specify proprietary fluid; check manual |
| Rotary screw (oil-flooded) | ISO VG 32–46 | Extended drain interval synthetics common |
| Reciprocating (small single-stage) | ISO VG 100 | Mineral or semi-synthetic |
| Reciprocating (large multi-stage) | ISO VG 150 | Mineral; high discharge temperature tolerance required |
| Rotary vane | ISO VG 46–68 | AW-grade mineral or synthetic |
For further context on compressor oil selection, see the AIMS Air Compressor Guide. See also the Industrial Lubricants Guide for a full overview of oil types and additive considerations across applications.
ISO VG for Chain Oil, Way Oil, and Other Industrial Applications
ISO VG grades are used across a broader range of industrial lubricants beyond hydraulic, gear, and compressor systems. The table below covers the most common additional applications encountered in Australian industrial maintenance.
| Application | Typical ISO VG Grade | Notes |
|---|---|---|
| Roller chain (conveyor, drive) | ISO VG 100–150 | Must penetrate chain joint; tacky additives common in chain-specific oils |
| Machine tool slideways (way oil) | ISO VG 32–68 | Requires stick-slip additive (fatty acid) — not interchangeable with plain hydraulic oil |
| Circulating systems (oil mist) | ISO VG 32–68 | Low viscosity for mist generation; R&O additive package |
| Plain (journal) bearings | ISO VG 32–68 | Depends on shaft speed and load; high-speed light bearings → lower grade |
| Rolling element bearings (oil bath) | ISO VG 68–150 | Consult bearing manufacturer speed/load tables |
| Turbine oil (steam/gas turbine) | ISO VG 32–68 | R&O inhibited; high oxidation stability required; no AW additives |
| Transformer oil | ISO VG 7–22 | Electrical insulating oil — specialist product, not general industrial oil |
Viscosity Index (VI) Explained
Viscosity Index (VI) is a dimensionless number that describes how much an oil's viscosity changes as temperature changes. A high VI means the oil's thickness stays relatively consistent across a wide temperature range. A low VI means the oil thins significantly at higher temperatures and thickens considerably at lower temperatures.
VI is calculated using ASTM D2270, based on kinematic viscosity measurements at both 40°C and 100°C. The higher the ratio of viscosity-at-100°C to viscosity-at-40°C, the higher the VI.
| Oil Type | Typical Viscosity Index | Temperature Stability |
|---|---|---|
| Naphthenic mineral oil | 0–60 | Poor — significant thinning at high temperature |
| Standard paraffinic mineral oil | 80–100 | Moderate — acceptable for controlled environments |
| HVI (High Viscosity Index) mineral oil | 100–130 | Good — suitable for wide temperature range applications |
| Group III hydrocracked / VHVI mineral oil | 120–140 | Very good — near-synthetic performance |
| PAO synthetic | 120–180+ | Excellent — stable across extreme temperature ranges |
| Ester synthetic | 150–200+ | Excellent — best natural VI of all base oil types |
In Australian industrial applications, VI becomes important for:
- Outdoor mobile equipment exposed to wide ambient temperature swings — cold mornings and hot afternoons in inland and alpine regions
- Equipment moved between climate zones (e.g. a fleet operating across both tropical far north Queensland and temperate southern states)
- Applications requiring single-fill year-round operation without seasonal oil changes
For equipment operating in stable indoor environments with controlled temperatures, standard mineral oil VI (95–105) is fully adequate. HVI or synthetic grades provide a benefit only where the temperature range actually demands them — paying for higher VI without the temperature variation to justify it delivers no measurable benefit.
Kinematic vs Dynamic Viscosity: What the Units Mean
Two viscosity measurements appear on oil data sheets and in technical specifications. Understanding which is which prevents misreading specifications.
Kinematic viscosity (unit: cSt — centistokes, or mm²/s) is the most common measurement in industrial oil specifications. It measures how fast a fluid flows under gravity. ISO VG grades are defined using kinematic viscosity at 40°C. This is what appears in Ahrefs data sheets for almost all industrial lubricants.
Dynamic viscosity (unit: cP — centipoise, or mPa·s) measures the force required to move one layer of fluid over another. At 40°C: dynamic viscosity (cP) = kinematic viscosity (cSt) × density (kg/L). For typical mineral oils with density ≈ 0.87 kg/L, ISO VG 46 has a dynamic viscosity of approximately 40 cP at 40°C.
In practice: if you are selecting industrial oil, you are working with kinematic viscosity in cSt. If you encounter dynamic viscosity in cP, divide by the oil's density (approximately 0.87 for most mineral oils) to convert to cSt.
How Temperature Affects Viscosity in Practice
Every oil thins as it heats and thickens as it cools. This is not a flaw — it is a fundamental property of all liquids. The questions that matter for maintenance are: does it thin too much at operating temperature, and does it thicken too much at cold start?
A practical reference: the hydraulic oil in most Australian industrial systems operates at 40–60°C in the reservoir under normal conditions. At this temperature, ISO VG 46 is performing at or near its rated 46 cSt viscosity. If the system runs consistently hot — reservoir temperature above 60°C — ISO VG 68 provides better film thickness. If the system starts cold in winter (below 10°C ambient) before reaching operating temperature, ISO VG 32 may start faster and with less cavitation risk.
The two-temperature viscosity measurement (at 40°C and 100°C) on a product data sheet gives you a picture of how the oil behaves across its operating range. A small drop in viscosity from 40°C to 100°C indicates high VI; a large drop indicates low VI and poor temperature stability.
Common Viscosity Grade Selection Mistakes
Using engine oil in hydraulic or gear systems. Engine oil contains detergents, dispersants, and friction modifiers incompatible with hydraulic pumps, seals, and gear surfaces. Viscosity equivalence does not make oils interchangeable. This is the most damaging substitution error in maintenance.
Going up a grade as a "safe" default. Thicker is not safer — it is a different specification. Using ISO VG 68 where 46 is specified causes cavitation on cold start, increased pressure drop through filters, sluggish actuator response, and higher operating temperatures from pumping resistance. Use the specified grade.
Ignoring the difference between ISO VG and AGMA grades. An AGMA 5 gearbox specification requires ISO VG 320 gear oil — not ISO VG 5. The AGMA number does not correspond to the ISO VG number. Always use the conversion table.
Assuming all ISO VG 220 gear oils are the same. ISO VG 220 with EP (extreme pressure) additives and ISO VG 220 without EP are different products for different applications. Plain ISO VG 220 industrial gear oil lacks the sulphur-phosphorus additives needed for high-contact-stress gear surfaces. Using plain oil where EP is required leads to surface fatigue and pitting.
Mixing grades to "get close." Mixing ISO VG 46 and 68 produces something in between — not the same performance as either. More critically, mixing additive packages from different manufacturers can cause sludge, foam, or additive precipitation. If a full drain and refill is not possible immediately, minimise the top-up quantity and flush at the first opportunity.
Frequently Asked Questions
What does ISO VG mean?
ISO VG stands for International Organisation for Standardisation Viscosity Grade. The number (32, 46, 68, etc.) represents the oil's nominal kinematic viscosity in centistokes (cSt) measured at 40°C, with a ±10% tolerance. Higher number means thicker oil. The system was established in 1975 to provide a single universal viscosity classification for industrial lubricants.
What is ISO VG 46 equivalent to in SAE?
ISO VG 46 is approximately equivalent to SAE 15W in terms of viscosity at 40°C. However, this is a viscosity comparison only — ISO VG 46 hydraulic or gear oil and SAE 15W engine oil are entirely different products. Engine oil contains additives (detergents, dispersants, friction modifiers) that are harmful in hydraulic and gear systems. Never substitute engine oil for industrial ISO VG oil based on viscosity equivalence alone.
What is ISO VG 32 equivalent to in SAE?
ISO VG 32 is approximately equivalent to SAE 10W in viscosity at 40°C. The same caution applies: this is a viscosity comparison, not a substitution guide. ISO VG 32 hydraulic oil and SAE 10W engine oil are not interchangeable.
Is ISO VG 46 thicker or thinner than ISO VG 68?
ISO VG 46 is thinner (lower viscosity) than ISO VG 68. The ISO VG number represents kinematic viscosity in cSt at 40°C — 46 cSt is thinner than 68 cSt. ISO VG 46 flows more freely, is better for cold-start conditions, and suits most Australian general industrial hydraulic applications. ISO VG 68 provides a thicker film and suits higher temperature or higher pressure applications.
What AGMA grade is equivalent to ISO VG 220?
ISO VG 220 is equivalent to AGMA 4. If a gearbox calls for AGMA 4 EP (extreme pressure) oil, the equivalent is ISO VG 220 with EP additive package. Verify that the EP specification matches — AGMA 4 without EP suffix requires plain ISO VG 220 industrial gear oil, not EP-grade.
What AGMA grade is equivalent to ISO VG 320?
ISO VG 320 is equivalent to AGMA 5. This is a common gearbox specification in Australian industrial equipment. ISO VG 320 EP gear oil is the standard product for this requirement.
Can I mix ISO VG 32 and ISO VG 46?
Blending ISO VG 32 and 46 will produce an intermediate viscosity, but the result is not a standard grade with known performance characteristics. More critically, mixing additive packages from different manufacturers — even within the same ISO VG family — can cause additive incompatibility, sludge formation, or foaming. If a top-up is unavoidable, minimise the quantity, use the same brand and type if possible, and flush the system at the next opportunity. Never mix mineral hydraulic oil with synthetic, water-glycol, or fire-resistant fluid.
What is the viscosity index (VI) and does it matter for my application?
Viscosity Index measures how much an oil's viscosity changes with temperature. A VI of 100 is typical for standard mineral oil. HVI oil has a VI of 140+ and maintains more consistent thickness across a wide temperature range. VI matters if your equipment operates across a wide ambient temperature range — outdoor plant in regions with cold mornings and hot summers, or equipment moved between climate zones. For equipment in a stable indoor environment, standard mineral oil VI is fully adequate.
What is the difference between kinematic and dynamic viscosity?
Kinematic viscosity (cSt or mm²/s) measures how fast a fluid flows under gravity. Dynamic viscosity (cP or mPa·s) measures the force required to move layers of fluid past each other. ISO VG grades and most industrial oil specifications use kinematic viscosity at 40°C. Dynamic viscosity in cP = kinematic viscosity in cSt × oil density (approximately 0.87 for mineral oil). In practice, if you are selecting industrial lubricants, you are working with kinematic viscosity in cSt.
Why does ISO VG 68 hydraulic oil look the same viscosity as ISO VG 68 gear oil?
Both have the same kinematic viscosity at 40°C — that is all ISO VG measures. The difference is in the additive package. ISO VG 68 hydraulic oil contains anti-wear (AW) additives, rust and corrosion inhibitors, and foam suppressants formulated for hydraulic pump surfaces and seals. ISO VG 68 gear oil contains extreme pressure (EP) additives, typically sulphur-phosphorus chemistry, formulated for the high-contact-stress surfaces of gear teeth. Using hydraulic oil where gear oil is specified (or vice versa) will cause accelerated wear and potential equipment damage despite matching ISO VG numbers.
What ISO VG grade does a rotary screw compressor use?
Most oil-flooded rotary screw compressors use ISO VG 32 or 46 fluid — but many manufacturers specify a proprietary synthetic or semi-synthetic compressor fluid rather than a standard industrial oil. The reason is that standard AW hydraulic oil can form varnish and carbon deposits at compressor operating temperatures, causing valve sticking and heat exchanger fouling. Always check the compressor manufacturer's specification before selecting a fluid. Using a non-specified oil can void the warranty and accelerate wear.
Where can I find the ISO VG specification for my equipment?
The primary source is always the equipment's service manual or OEM maintenance documentation. If that is not available: (1) check the equipment's lubrication plate — many machines have a nameplate or label specifying the required lubricant type and ISO VG grade; (2) contact the manufacturer or their Australian distributor; (3) use the tables in this guide as a starting reference only. Using the wrong grade based on a general guide carries risk — OEM specification overrides all general recommendations.
