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Air compressor lubrication

Where to lubricate, oil types and viscosity (ISO VG), and replacement guide. Inspection and replacement intervals and oil types follow the operation manual of your machine first. The intervals here are examples for specific models from published sources and vary with running hours, ambient temperature, and dust. Do not remove the safety valve or raise its setting. Leave the dryer refrigerant, disassembly and overhaul of the unit, and electrical work to the manufacturer, dealer, or qualified persons. The key points of the regulations were checked on e-Gov on 2026-10-06

⛽Lubrication points and oils

Location	Machine	Oil (example)	Interval guideline
Crankcase of an oil-lubricated reciprocating compressor	Reciprocating	Manufacturer's genuine reciprocating compressor oilAlso check the oil for emulsification every day. Running with no oil or with dirty oil causes seizure (ANEST IWATA). The Japan Society of Industrial Machinery Manufacturers lists topping up, inspecting, and changing lubricating oil as a typical inspection item	Check the oil level daily. Full oil change at the first 200 hours (1 month), then every 1,250 hours (6 months) (ANEST IWATA CLP37EF example)^[1][2][3]
Oil of an oil-lubricated screw compressor (separator tank)	Screw	Genuine oil made for screw compressorsIn a screw compressor, the oil also handles cooling and sealing in the compression chamber, in addition to lubricating the bearings. When it degrades, cooling and sealing drop, leading to abnormal temperature and wasted electricity (ANEST IWATA). When the separator is clogged, replace the oil, oil filter, and separator together (Atlas Copco)	Replace the oil, oil filter, and oil separator element every 2 years (8,000 hours) (ANEST IWATA LRS-220BD example; the basis is 4,000 hours of operation per year)^[4][3][5]
Motor and compressor bearings (grease)	Common	Manufacturer-specified greaseMeiji Machine's oil-free units call for replacing the piston rings, guide rings, and bearings at 8,000 hours (packaged type) or 10,000 hours (general-purpose type)	Motor checks (grease replenishment, insulation resistance) are part of the periodic inspection. For oil-free reciprocating units, check the ball bearings and needle roller bearings for rotation and grease leakage every year (3,000 hours) (example from Meiji Machine)^[3][6]

🛢Oil types and how to choose

Genuine manufacturer compressor oil: Lubricates the compressor (in screw types it also cools and seals). ANEST IWATA says that, compared with cheap commercial oils, its genuine oil changes less in viscosity with temperature, is less prone to forming carbon (carbonized lubricant deposits), and lubricates better. JSIM also asks that genuine parts be used for replacements^[2][3][7]
Watch for carbon (carbonized lubricant) deposits: In oil-lubricated units, the oil turns to mist in the compression chamber, is exposed to high temperature and pressure, and oxidizes and breaks down into carbon deposits. If deposits build up in the separator element or piping, oil soaks into them and reaction heat accumulates, which can cause ignition and, in the worst case, an explosion (JSIM). Genuine oil suppresses these deposits (ANEST IWATA)^[3][2]

📚Sources

Items without a mark are those on which two or more materials from different publishers agree. Values and intervals are governed by each machine's specifications. The text is summarized in Kezuriba's own words.