ISO VG (Viscosity Grade) is a classification system for industrial lubricants defined by ISO 3448. Each grade corresponds to a kinematic viscosity midpoint at 40°C in centistokes (cSt). For example, VG 46 means the oil has a midpoint viscosity of 46 cSt at 40°C, with an allowed range of 41.4–50.6 cSt (±10%).

How to choose the right viscosity grade?

The choice depends on the application: VG 32–46 for hydraulic systems, VG 68–150 for industrial gearboxes, VG 220–460 for heavy-duty enclosed gears, VG 10–22 for high-speed spindles. Always consult the equipment manufacturer's recommendations.

What is the difference between ISO VG and SAE?

ISO VG grades are based on kinematic viscosity at 40°C and are used for industrial lubricants. SAE grades are used for automotive oils: SAE crankcase grades (e.g. 10W-30) are measured at 100°C, while SAE gear grades (e.g. 75W-90) use a different viscosity range. The two systems do not directly correspond.

溫度如何影響黏度？

Oil viscosity decreases as temperature increases. The ISO VG system specifies viscosity at 40°C. The rate of change with temperature is described by the Viscosity Index (VI). A higher VI means less viscosity change with temperature. Typical mineral oils have VI 80–100; synthetic oils can reach VI 150+.

cSt stands for centistokes (mm²/s), the unit of kinematic viscosity. It measures how fast a fluid flows under gravity. 1 cSt = 1 mm²/s. Dynamic viscosity in cP (centipoise) = kinematic viscosity in cSt × density in g/cm³.

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潤滑油黏度等級 — ISO VG

依 ISO 3448 查詢 ISO VG 黏度等級。輸入 40 °C 時的運動黏度以找到對應等級，或選擇 VG 等級以查看黏度範圍與典型應用。

ISO 3448 VG 2 – VG 1500 cSt @ 40 °C

40 °C 時的黏度 (cSt = mm²/s)

或選擇 ISO VG 等級

快速預設

結果

ISO VG 等級

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黏度範圍（最小值 – 最大值）

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中間黏度值

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典型應用

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ISO 3448 黏度分類

ISO 3448 為工業潤滑油定義了 18 個黏度等級。每個等級以一個數字標識，該數字等於 40 °C 時的名義運動黏度中間值（單位：厘斯 cSt）。允許範圍為中間值的 ±10%。

Range = Midpoint × 0.9 to Midpoint × 1.1 [cSt at 40 °C]

完整 ISO VG 表

ISO VG	最小值 (cSt)	中間值 (cSt)	最大值 (cSt)	典型應用

應用指南

應用	推薦 ISO VG
高速主軸	VG 10 – VG 22
液壓系統	VG 32 – VG 46
一般機械潤滑	VG 46 – VG 68
工業齒輪箱	VG 68 – VG 150
重型封閉式齒輪	VG 220 – VG 460
極重型 / 低速齒輪	VG 680 – VG 1500

注意： ISO VG 等級僅規範 40 °C 時的黏度。實際運轉黏度取決於服務中的油溫。請使用黏度指數 (VI) 來估算其他溫度下的黏度。