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Home›Knowledge base›Vacuum pump oil: when and why to change it
4REF · GuideNr 06Maintenance
Maintenance

Vacuum pump oil: when and why to change it

Spent oil means a shallower vacuum and a shorter pump life. Simple rules that extend equipment life.

4R
4REF expert team
April 18, 2026 · 4 min read

Oil absorbs moisture

The oil in a vacuum pump binds the moisture and contaminants pulled from the system. Cloudy, milky oil has lost its properties and the pump will no longer reach a deep vacuum.

Change after a wet system

After any badly waterlogged system, change the oil the same day. Running on spent oil carries moisture into the next system and accelerates internal corrosion.

Before long storage

Before storing the pump for a while, change to fresh oil — acidic breakdown products attack the seals during downtime. A short flush with fresh oil also cleans the chamber.

Use the right oil

Use oil made for vacuum pumps (e.g. Wipcool WPO-2 or Fieldpiece OIL32) of the correct viscosity. Engine or hydraulic oil is unsuitable and shortens pump life.

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