I use the Husky synthetic blend compressor oil from Home Depot. Compressor has lasted 2+ years with it so it must be good. From what I have read a decent non-detergent motor oil will werq in them also. Here is some info that werqs for me with the Yong Heng compressors.
The
Yong Heng "simple version" least expensive does not have a water separator you need one.
The "auto stop" version shuts off near 3000psi.
So you likely want the "Hardcover" or 'Set pressure' versions your choice on the 110V or 220V.
https://www.aliexpress.com/item/32824234795.html?spm=a2g0o.store_home.productList_13760454.subject_2 Keep them cool, the oil topped off to the red circle in the sight glass, and don't fill past their spec which I think is 4350psi, a little less is better than the max, and the Yong Heng should last for years unless you get a bad one. I did my first oil change at about an hour far longer, between changes, after that.
I have two YH compressors. Bought the second as a backup for the first as I fergot to turn on the coolant pump several times and overheated it until it smoked. It did not like it but it still runs fine. Still I did not trust it after that. I added a switched outlet, to the system, so it turns the pump on before the compressor will power up to keep me from doing that from now on. The second one, my back up unit, died in about two months bad QC from the factory. Cost me a $12, for a new second stage piston, and an hour to repair it. Then to add insult to injury I fergot to put the oil in, the latest unit, after I put it back together and ran it for a couple of minutes without any oil. Somehow it still runs fine. The #1 unit that I was worried about, cuz I overheated it so many times, just kept on filling my guns and tanks till I got #2 repaired and retired it.
I do not fill past 4200psi as when I do, all too often, I blow a burst disc. This does not happen on the first or second fill but soon thereafter.
The temperature sensor only measures head temperature so running it much over 20-30 minutes can overheat the motor and other parts even if ice is used in the coolant. Ice or a container of it, in the coolant, is a good idea especially if you are like me and do not use the full five gallons of water as suggested in the manual.
Keep your water supply level with the compressor to be kind to the pump and assure a good supply of coolant goes through the compressor.
Keep your moisture filters, guns and tanks being filled above the compressor to help keep the moisture out.
Purge the system of moisture for a couple of seconds every five minutes while in use.
Change out your small YH filter every twenty minutes and set the old one out to dry and use later.
Add a better filter if needed to be sure more moisture and any oil smell is removed from the system. Many of us use this Tuxing three media filter although, if you feel the need, you can change media types at any time.
https://www.aliexpress.com/item/32891898253.html A smaller one will probly do for many.
https://www.aliexpress.com/item/4000960926898.html?spm=a2g0s.9042311.0.0.2a034c4dL0nrJU. Bleed the pressure before you turn the unit off and let it run a few seconds to get the better part of the moisture out of the system. I have found that I blow less burst discs if I bleed before shutting down so I do this religiously.
Let the coolant pump run for a few minutes after shutdown to cool things off.
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Here is a video on how to fill a SCBA tank.
https://www.youtube.com/watch?time_continue=157&v=_grx5p_R8D4&feature=emb_title 
