If CH has the same sight, do you know your model number? I'll download a manual from their website and use it instead. The Ironhorse manual is worthless.
"Plug into a the wall. Turn unit to the on. Blow the air. Dont not mis-use."
Regarding the oil, I found this that says like you did, any 30 wt non detergent will do fine.
What's the difference between compressor oil and regular non-detergent oil?
That doesn't include my bottle of Penzoil though, because any oil listed as SAE for gas engines IS detergent oil.