Oil Viscosity Chart
The numbers on an oil bottle describe how thick the oil is when cold and when hot — but “5W-30” is a set of laboratory limits, not a temperature rating. This chart explains what each SAE grade actually requires, looks up any grade you type, and estimates how an oil’s viscosity changes with temperature using the two values printed on its technical data sheet.
Oil viscosity chart and calculator
Viscosity at any temperature (from a data sheet)
Oil Viscosity Reference Pack
Printable SAE J300 and ISO VG viscosity charts, a spreadsheet that estimates viscosity at any temperature from data-sheet values, and a vehicle and equipment oil change log.
- SAE chart (PDF/XLSX)
- ISO VG chart (PDF/XLSX)
- Estimator (XLSX)
- Oil change log (PDF/DOCX/XLSX)
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What the numbers on an oil bottle mean
Engine oil grades come from the SAE J300 standard. A multigrade such as 5W-30 has two parts. The number before the W (“winter”) is set by low-temperature tests: how easily the engine can crank and whether the oil pump can move the oil when it is very cold. The number after the dash is set by viscosity at engine operating temperature: kinematic viscosity at 100 °C plus a minimum high-temperature high-shear (HTHS) viscosity at 150 °C. Lower first numbers flow better in the cold; higher second numbers are thicker when hot.
SAE J300 winter (W) grades
| Grade | Max cranking viscosity (CCS) | Max pumping viscosity (MRV) | Min viscosity at 100 °C |
|---|---|---|---|
| 0W | 6,200 mPa·s at -35 °C | 60,000 mPa·s at -40 °C | 3.8 cSt |
| 5W | 6,600 mPa·s at -30 °C | 60,000 mPa·s at -35 °C | 3.8 cSt |
| 10W | 7,000 mPa·s at -25 °C | 60,000 mPa·s at -30 °C | 4.1 cSt |
| 15W | 7,000 mPa·s at -20 °C | 60,000 mPa·s at -25 °C | 5.6 cSt |
| 20W | 9,500 mPa·s at -15 °C | 60,000 mPa·s at -20 °C | 5.6 cSt |
| 25W | 13,000 mPa·s at -10 °C | 60,000 mPa·s at -15 °C | 9.3 cSt |
The test temperatures are where the oil must still meet the limits — they are not the lowest temperature at which you may use the oil, although colder climates generally call for lower W numbers.
SAE J300 hot grades
| Grade | Viscosity at 100 °C (cSt) | Min HTHS at 150 °C (mPa·s) |
|---|---|---|
| 8 | 4 to below 6.1 | 1.7 |
| 12 | 5 to below 7.1 | 2.0 |
| 16 | 6.1 to below 8.2 | 2.3 |
| 20 | 6.9 to below 9.3 | 2.6 |
| 30 | 9.3 to below 12.5 | 2.9 |
| 40 | 12.5 to below 16.3 | 3.5 for 0W-40, 5W-40, 10W-40; 3.7 for 15W-40, 20W-40, 25W-40 and SAE 40 |
| 50 | 16.3 to below 21.9 | 3.7 |
| 60 | 21.9 to below 26.1 | 3.7 |
The low grades 8, 12 and 16 were added for engines designed for very thin, fuel-saving oils. Use them only where the manufacturer specifies them.
How multigrade oils work
A plain (monograde) oil thins a lot as it heats up. Multigrade oils start from a thinner base oil, which helps in the cold, and use viscosity index improvers — polymers that limit how much the oil thins when hot — so the same oil can pass both a winter test and a hot-viscosity test. The viscosity index (VI) printed on data sheets describes how much viscosity changes between 40 °C and 100 °C: the higher the VI, the flatter the curve.
Worked example
A technical data sheet for a 5W-30 lists 60 cSt at 40 °C and 10.5 cSt at 100 °C. Putting both values into the estimator gives about 150 cSt at 20 °C, 496 cSt at 0 °C and 4.5 cSt at 150 °C — roughly 47 times thicker at 0 °C than at 100 °C. Its 10.5 cSt at 100 °C sits in the SAE 30 band (9.3 to below 12.5), and 60 cSt at 40 °C falls between ISO VG 46 and VG 68, so it would not be labelled with an ISO grade. These are illustrative numbers — use the values from your own oil’s data sheet.
ISO viscosity grades for industrial oils
| ISO VG | Viscosity at 40 °C (cSt), ±10% | Typical uses |
|---|---|---|
| 10 | 9.0–11.0 | Spindle oils |
| 15 | 13.5–16.5 | Light hydraulic, spindles |
| 22 | 19.8–24.2 | Light hydraulic |
| 32 | 28.8–35.2 | Hydraulic, turbines, air compressors |
| 46 | 41.4–50.6 | Hydraulic (very common) |
| 68 | 61.2–74.8 | Hydraulic, compressors |
| 100 | 90.0–110.0 | Compressors, light gears |
| 150 | 135.0–165.0 | Gears, bearings |
| 220 | 198.0–242.0 | Enclosed gears |
| 320 | 288.0–352.0 | Gears |
| 460 | 414.0–506.0 | Heavy gears, worm gears |
| 680 | 612.0–748.0 | Heavy, slow gears |
ISO grades (ISO 3448) are named after the midpoint viscosity at 40 °C. Equipment manuals specify the grade; typical uses above are general examples.
Engine oil vs gear oil numbers
Gear oils use a separate scale, SAE J306, so the numbers are not comparable with engine oil grades: a 75W-90 gear oil is roughly as thick at 100 °C as an SAE 40 to 50 engine oil, even though “90” sounds much thicker. Always use the scale that applies to the part you are filling.
Choosing the right oil
- Use the grade in the owner’s manual; many manuals list a preferred grade and permitted alternatives by climate.
- Match the required performance specification or manufacturer approval as well as the grade — for example an API, ILSAC or ACEA category, or a carmaker’s own approval.
- Thinner-than-specified oil can reduce protection under high load; thicker-than-specified oil can slow cold-start lubrication and affect systems such as variable valve timing.
- For older or modified engines, follow a specialist’s advice rather than a general chart.
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Frequently asked questions
What does the W in 5W-30 mean?
Winter: it shows the oil passed SAE’s low-temperature cranking and pumping tests for that grade.
Is 5W-30 thicker than 5W-20?
Yes, at operating temperature — SAE 30 requires 9.3 to below 12.5 cSt at 100 °C, SAE 20 requires 6.9 to below 9.3.
What is HTHS?
High-temperature high-shear viscosity at 150 °C, a measure of oil film strength in bearings and piston rings.
What is ISO VG 46?
An industrial oil grade with 41.4–50.6 cSt at 40 °C, common for hydraulic systems.
Can I use 10W-40 instead of 5W-30?
Only if your manual permits it; follow the manufacturer’s grade and specification.
How accurate is the temperature estimate?
Good between about 0 and 150 °C using two data-sheet points; not for extreme cold.