How Do You Change Your Oil and Filter on a Reciprocating Compressor?

Why this maintenance matters 

• Oil condition affects heat, wear, and performance. Old oil can carry contaminants and break down under heat, which increases friction and temperature.
• A clogged inlet filter makes the pump work harder. Restricted airflow can reduce capacity and raise operating temperature.

What you’ll need: 

From the provided procedure, gather: 

• Approved compressor oil (correct type/viscosity for your model) 
• Drain pan (and absorbent pads if required by your site) 
• Wrenches (typically for drain plug and filter housing fasteners) 
• New inlet filter element (correct part number/size)
• PPE: safety glasses, gloves, and any site-required protection

Nice-to-have: funnel, clean rag, torque wrench (if you have torque specs), label/tag for date-hours, sealable waste-oil container. 

1. Plan for downtime. Oil needs time to drain and you’ll want to do a quick run check afterward.
2. Warm the compressor slightly. A short warm-up helps the oil drain more completely. Do not run it long enough to get the crankcase too hot to work around.
3. Shut down and isolate energy. Power OFF and follow lockout/tagout.
4. Depressurize fully. Bleed system pressure down to zero before opening any plugs or covers. 

Hazards to keep in mind 

• Hot surfaces and hot oil (burn risk)
• Stored air pressure (sudden release risk)
• Slips from oil drips (housekeeping matters)

 1. Warm slightly for drainage

• Run just long enough to slightly warm the oil for better flow, then shut down.

2. Power OFF, depressurize, then drain

• Confirm power is OFF and the unit is depressurized.
• Position a drain pan under the crankcase drain. 
• Remove the drain plug and let oil drain completely. 
• Remove the fill cap (or breather/fill cap) to speed drainage and reduce glugging.

Pro tip: If oil drains very slowly, confirm the fill cap is loosened/removed. Also verify you opened the correct drain point (crankcase, not receiver tank condensate drain). 

  3. Reinstall drain plug

• Wipe the area clean.
• Reinstall the drain plug. 
• If your plug uses a sealing washer or thread sealant per OEM guidance, replace/apply as specified in your manual.

   4. Refill with approved oil

• Add the approved oil through the fill port.
• Fill to the correct level (typically midpoint of a sight glass, or to the dipstick mark if equipped).
• Reinstall the fill cap. 

Avoid common mistakes 

• Overfilling. Too much oil can foam and raise crankcase pressure.
• Mixing oil types. Stick to the approved oil called out by your compressor OEM.

Many recip compressors use an inlet filter element at the pump intake (sometimes a small canister or housing on the inlet). The provided steps describe a simple cover-and-element swap.  

1. Locate the inlet filter housing on the pump intake.
2. Remove the cover. 
3. Remove the old filter element and install the new one. 
4. Reinstall the cover and snug fasteners evenly. 

Quick check: Look for cracks in the housing, hardened seals, or missing gaskets. Air leaks here can pull unfiltered air into the pump. 

Troubleshooting after an oil/filter change 

Oil looks milky or foamy 

• Possible moisture contamination, wrong oil, or overfill. Drain and refill with the correct oil if needed, and review operating conditions.

Compressor still runs hot 

• A clean inlet filter helps, but overheating can also come from poor ventilation, dirty coolers/fins, incorrect oil, high ambient temperature, or excessive duty cycle.

Oil leak at drain plug 

• Plug not seated, damaged threads, missing sealing washer, or debris on the sealing surface. Shut down, depressurize, correct the seal, and recheck.

Reduced output after filter change 

• Verify the element is the correct type and installed in the right orientation. Confirm the housing is sealed and not pulling bypass air.