How to do it

Cleaning

UNPLUG THE AIR COMPRESSOR
Wipe down the exterior with a rag, focusing on clearing dust off the motor, any moving parts.

The bottom of the air compressor has a valve for quickly evacuating water that collects at the bottom of the air tank.

Grab a pan or bucket
PUT ON SAFETY GLASSES
With the bucket positioned to catch water, slowly open the valve till water and air start to shoot out.
As soon as it stops sputtering, close the valve. If the water is slightly red, that is ok. If there is noticeable sludge, inform the manager.

UNPLUG THE AIR COMPRESSOR
Grab a 1qt bottle of new oil, a funnel, an oil pan or bucket, and a few clean rags
There is a valve below the motor for draining the oil. Position the bucket under the outlet and open the valve. Let the oil drain completely and set aside.
On the top of the motor is a cap. Unscrew this and place the funnel in it. Pour the new oil in, being careful not to spill.
Once oil reservoir is filled, drain a little bit of the oil to drain any remaining old oil. If it drains clear it is good to go.
Screw the top cap back on, make sure the drain valve is closed, and clean up any oil spills.
Use the funnel to pour the old oil into the bottle. The used oil should be taken to an auto garage or any place that can dispose of oil.