Hydraulic Oil: Understanding HM 32, 46 and 68 Grades

The wrong hydraulic oil wears out pumps and cylinders prematurely and reduces system efficiency. The ISO VG grade (32, 46, 68) indicates viscosity at 40°C and should match the equipment manufacturer's specification.

2026-09-15·5 min read

HM 32, 46, 68: what's the difference?

HYDRO HM 32 — systems running at low temperature or needing a fast response (precision machine tools, light hydraulic systems).
HYDRO HM 46 — the most common grade, suited to most presses, cylinders and industrial or agricultural hydraulic systems in temperate conditions.
HYDRO HM 68 — equipment running at high operating temperatures or under heavy loads (construction machinery, mining equipment).

Why oil cleanliness matters as much as viscosity

In a hydraulic circuit, particle contamination is the leading cause of pump failure. The HYDRO range is formulated with anti-wear (HM) additives that protect metal surfaces even under light contamination, but clean storage and well-maintained filters remain essential.

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Frequently Asked Questions

In Short

How do I know which HYDRO grade to use?

Check your equipment's nameplate or manual: the manufacturer usually specifies the recommended ISO VG grade (32, 46 or 68).

Do you supply hydraulic oil in bulk for industry?

Yes, the HYDRO range is available in jerrycans as well as drums for industrial and mining sites — contact us for a volume quote.

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