Don't use regular motor oil or synthetic motor oil. You need high pressure air compressor oil like https://www.augustindustries.com/shopexd.asp?id=613&bc=no
or the Coltri equivalent.
The high pressure compressor oil is formulated to resist detonation at the high pressure/temperature of a high pressure compressor. Motor oils are not suitable for this application.
Tank Filling procedure...
roper filling is to start with the tank main valve and tank fill whip bleed valve closed.
Close the bleed at the top of the PMV, but open the manual drain at the water/oil separator.
Set the auto shutoff pressure to 4500.
Start the compressor. Because the drain valve is open, it will see no load. Let it warm up for about 10-15 seconds to distribute its oil before it gets loaded.
Close the drain valve. The pressure will steadily rise in the compressor. You should see the Carette gauge gradually rise. At the point the PMV opens, you will notice the rate of pressure rise drop for a moment. That's probably around 2200 PSI.
Let the pressure continue to build to approximately equal to your tank pressure. Gradually open the tank valve to full opening. This lets compressed air enter the tank. The timing of opening the tank when the compressor reaches tank pressure is to avoid suddenly loading the compressor with full tank pressure.
Don't keep the compressor running too long without a path for air to exit. You don't want to over pressure the compressor. The auto shut off should kick in before something goes awry, but it is best to keep an eye on things until you know all is functioning well. On my first run, I intentionally set the auto shutoff low so I could verify its function.
During tank filling, the Carette pressure gauge should read pretty close to what your tank gauge reads. If they are grossly mismatched, something is impeding flow and/or you have a leak at the fill whip bleed. If the gauges are way off match, stop the compressor and troubleshoot before continuing.
You will see the pressure in the compressor rise as the tank fills.
Let the Carette auto drain fire every 10 minutes for about 2-3 seconds. You can also manually drain the separator, but the auto drain should do the work for you.
Once the tank reaches fill target pressure (4500 PSI), turn off the compressor.
Close the tank main valve.
Open the manual drain valve and bleed valve at the top of the PMV.
Turn on the Carette and let it run for 3-4 minutes without a load to clear out its cylinders of any residual moisture.
Turn off Carette and close the drain and PMV drain.
Open your tank bleed valve to ensure the hose is depressurized.