This is the page where we get into discussing the actual oil change process.
If, after you have read the information, you have any questions, you can ask them on this page.
I have posted a photo of my DIY compressor, focussing on the compressor head, and the components that you will want to identify on your air compressor when it comes time for an oil change.
Not every compressor is the same, yet all oil lubricated units will have an oil fill port of some sort, and that port will allow oil poured into your compressor to flow down to enter the oil sump located under the piston head assembly.
Do yourself a favor and keep a small funnel handy when you go to pour oil back in. Otherwise, you may cause yourself a bit of a mess by spilling the oil as you pour. This is the voice of experience!
Normally the cover for the oil fill port is vented. Your compressor consumes a little (or sometimes a lot) of oil as it runs, and if the port were not vented, eventually a vacuum would form in the sump which would limit the efficiency of the lubrication process.
Your compressor too must have some method of determining how much oil you need to add to top up your compressor sump. If not a sight glass like the one in the photo above, then probably the cap of your oil fill port also contains a dipstick.
Overfilling the oil sump will lead to maintenance issues for your compressor.
You must keep the oil level topped up (the cheaper the oil-lubed compressor, the more oil it uses, it seems) and you must not overfill it.
The bigger the compressor, the more oil it will need, of course. Mine only holds a few ounces, so I take real good care not to overfill, but at the same time, I check the oil level every time I go to turn the compressor on, as it doesn't take long for it to go through those few ounces of oil, either.
Some compressors (the more expensive types I think) actually have an extension on the drain port to allow easier collection of the oil.
I've used a flat cake tin that slides in under the drain port. Or, you can fashion a drain funnel from a sheet of tin foil (folded a few times to make it more rigid) to help the oil to run into a catch bin of some sort.
Draining the compressor oil can get really messy if you don't contain the flow of used oil, and it is a witch to clean up. Take a care.
That's it. You're done.