3 months isn't a terribly long time. If it is oil filled, you might check/change the oil and filter if it has one. As mentioned, drain the tank and check the condition of it. Rusty tank is a primary concern, of mine anyway. :smile:I bought a used Sears Craftsman compressor which has not been used for three months. Is there anything I need to check or change before I start it up for the first time?