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Lubricant Grade Decoder

Cross-reference ISO VG, AGMA, SAE engine, SAE gear, and NLGI. Type one grade, get the rest.

Lubricant grades come from several standards that do not line up by number, which is how an SAE 90 gear oil can sit near the same ISO VG band as an SAE 50 engine oil while looking larger by grade number. This decoder takes a grade on a supported scale and reports the local approximate relationship to the other scales, anchored to the ISO VG 40 C viscosity band when there is an oil row. It also keeps the source boundary visible: SAE engine and gear scales are separate, AGMA and SAE cross-references are approximate comparison rows, NLGI grades grease consistency rather than oil viscosity, and product data sheets, OEM specifications, additive package, compatibility, operating conditions, and qualified review still govern real lubricant selection.

Pro Tip: Use ISO VG or the product data sheet viscosity as the comparison anchor, not SAE numbers alone. SAE engine and SAE gear classifications are separate scales, and multigrade oils bring cold-cranking, pumping, HTHS, shear stability, and viscosity-index behavior that this lookup does not model.

Once you have the grade, estimate the relube or oil-change interval with the

Lube Interval Calculator →

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Lubricant Grade Decoder
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How It Works

  1. Enter a grade

    Type a supported planning input such as ISO VG 68, AGMA 5, 10W-30, SAE 90, or NLGI 2.

  2. Read the scale it belongs to

    The decoder identifies whether the input is ISO VG, AGMA, an SAE engine grade, an SAE gear grade, or an NLGI grease consistency grade.

  3. Review the local comparison

    For oils, it shows the ISO VG row, the 40 C viscosity band, and approximate AGMA and SAE engine and gear comparison values.

  4. Heed the engine-vs-gear note

    The decoder flags that engine and gear SAE numbers are different scales, so grade numbers alone are not a substitution basis.

  5. Verify before specifying

    Check current ISO, SAE, AGMA, ASTM/NLGI, product data sheet, OEM specification, additive package, compatibility, and qualified review before selecting or substituting a lubricant.

Built For

  • A millwright screening whether a shop label such as "SAE 90" is in the same local comparison band as an ISO VG 220 callout.
  • A maintenance tech translating an old AGMA 5 note into an ISO VG planning row before checking the current standard and product data sheet.
  • A mechanic checking why a 10W-30 hot grade is only a rough comparison to an ISO VG row.
  • A planner separating grease consistency (NLGI) from base-oil viscosity, thickener, additive, and compatibility requirements.
  • Anyone confused about why the gear oil number is so much bigger than the engine oil number.

Features & Capabilities

Source-boundary lookup

ISO VG, AGMA, SAE engine, SAE gear, and NLGI rows are shown with visible source and verification warnings.

Engine-vs-gear warning

The separate SAE engine and gear scales are surfaced on every oil decode.

Grease handled separately

NLGI is reported on its consistency axis and is not converted into an oil viscosity grade.

Approximation flagged

Cross-references are labeled approximate because the scales use different reference temperatures and bands.

Comparison

ISO VG cSt at 40 C AGMA SAE engine SAE gear
46 41.4-50.6 1 15W / 20 75W-80W
68 61.2-74.8 2 20 80W
100 90-110 3 30 80W-90
150 135-165 4 40 85W-90
220 198-242 5 50 90
320 288-352 6 60 90-140

References

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Frequently Asked Questions

Not by the local comparison row used here. Both sit near ISO VG 220, but the conclusion for a real product still depends on the product data sheet, SAE standard edition, additives, OEM requirement, operating temperature, and service.
The ISO VG number is tied to a 40 C kinematic-viscosity class. The app shows the local band for lookup context, but exact row reconciliation remains tied to the current licensed ISO standard and the product data sheet.
This app shows local approximate AGMA-to-ISO rows for planning context. AGMA EP and R&O labels can share viscosity while differing in additive package, and gear manufacturers can require more than a viscosity grade.
No. NLGI grades the consistency of a grease using worked penetration, not base-oil viscosity. The base oil inside a grease has its own viscosity, and compatibility, thickener chemistry, pumpability, temperature, and OEM requirements must be checked separately.
The decoder uses the SAE 30 hot grade for a rough local comparison, but engine oils are multigrade and defined by more than 40 C kinematic viscosity. Check the product data sheet and OEM requirement for a real substitution decision.
Disclaimer: Viscosity cross-references returned by this decoder are approximate local comparison rows. The scales use different reference temperatures and overlapping bands, multigrade oils include cold and high-temperature requirements not modeled here, and NLGI grades grease consistency rather than viscosity. Always confirm the current governing standard, product data sheet, OEM specification, additive package, compatibility, application temperature, load, contamination, oil-analysis context, warranty, and qualified review before selecting or substituting an oil or grease. This tool is preliminary reference support only.

Learn More

Shops & Outbuildings

Lubricant Viscosity Grade Boundaries

How ISO VG, AGMA, SAE engine, SAE gear, and NLGI labels relate, with product data sheet, OEM, compatibility, and source-gap warnings.

Read Guide →

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