Industrial MRO Reference Library · Wall Charts

Viscosity Equivalents — ISO VG, SAE & AGMA

Approximate links between ISO VG grades, AGMA gear lubricant numbers and SAE engine and gear oil grades. SAE grades are defined differently, so their equivalents are only a rough guide.

Ref MRO-0084ISO 3448SAE J300SAE J306ANSI/AGMA 9005

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

Oils are graded by several different systems:

  • ISO VG (ISO 3448): viscosity at 40 °C. Used for industrial oils.
  • AGMA numbers (ANSI/AGMA 9005): industrial gear lubricant grades. Each AGMA number is tied to an ISO VG.
  • SAE J300: engine oil grades, defined by viscosity at 100 °C and by cold-temperature tests.
  • SAE J306: automotive gear oil grades, also defined at 100 °C and at low temperature.

Because SAE grades are measured at a different temperature, any SAE-to-ISO link depends on the oil's viscosity index. The SAE columns are approximate.

How to use it

  • Start from the grade the equipment maker calls for. Use this chart only to see roughly where another system's grade falls.
  • For an exact substitute, compare the actual viscosity at 40 °C and 100 °C on both products' data sheets.
  • Do not swap engine oil and gear oil because the viscosity looks similar. The additive packages are different.

Equivalents chart

ISO VGAGMA numberSAE engine oil (approx.)SAE gear oil (approx.)
22—5W—
32010W75W
46115W to 2075W
6822080W
10033080W to 85W
15044085W to 90
22055090
3206—90 to 140
4607—140
6808—140 to 250
10008A—250
15009—250

AGMA "EP" and "Comp" suffixes (such as 5 EP or 7 Comp) show extreme pressure or compounded oils of the same viscosity.

Key points

  • AGMA to ISO VG is a direct match. SAE equivalents are rough and vary by product.
  • SAE gear oil numbers are higher than engine oil numbers for similar viscosity. An SAE 90 gear oil and an SAE 50 engine oil fall close to the same ISO VG.
  • Multigrade oils (such as 15W-40) cover a range, so a single ISO VG cannot describe them.

Common mistakes

  • Treating an SAE number as a direct ISO VG conversion.
  • Replacing an industrial gear oil with an automotive gear oil without checking additives and seal compatibility.
  • Ignoring the "EP" or "Comp" part of an AGMA grade.

Governing standards: ISO 3448; ANSI/AGMA 9005 (industrial gear lubrication); SAE J300 (engine oil viscosity); SAE J306 (automotive gear lubricant viscosity); lubricant maker data sheets.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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