To all newbies and users of inexpensive Chinese compressors, please consider. Those two page Chinglish manuals that accompanied your compressors were written by non-English speaking writers and their terminology doesn't translate literally. Instead of a "burst disk" they say "explosion proof safety device". Instead of non-detergent high pressure compressor oil, they substitute #46 hydraulic fluid.
Centercut, Brian 10956, T3PRanch, and JimNM are experienced compressor owners and know what they are advising. If you are spending good money for a compressor which is being pushed to it's limits to produce 4500 psi air without breaking, why would you not buy insurance using quality oil? The biggest owner error posted over and over on these forums is owners trying to save money by using #46 hydraulic fluid because the Chinglish owner pamphlet says to. DON'T. That's why the exhaust stinks, the fluid turns black in an hour, and the little compressor needs replacement parts. Motor oil is as bad for compressors as hydraulic fluid. Unless you buy NON-detergent synthetic oil, motor oil leaves burnt residue in check valves and prematurely wears out the plastic resin piston rings. I've rebuilt compressors for guys who were getting black goo out of their bleeder valve and pressure wouldn't build as fast as the temperature rose.
Use a premium high pressure compressor oil. What you spend on oil will be saved on fewer repairs. There are many choices of high pressure compressor oils I use Chemlube CF500 from Filtertechs.com. I've owned 4 oil filled compressors over 14 years with no failures. This oil costs me $15 a quart and is changed annually. One quart of oil provides two oil changes on my dive compressor but 3 on a Yong Heng. Isn't your Yong Heng worth protecting annually for 1/3 the cost of a tin of pellets? It makes no sense to me to pay $15 for 100 FX slugs yet balk at the cost of 3 oil changes for the same $15 expenditure.
The alternative is to save a few dollars, breathe in the stench of burnt hydraulic fluid and keep the vendors on Aliexpress happy with repair parts sales. After all, the manual says so. Would you clean your PCP with Hoppe's #9 if you knew it degraded the o-rings? Of course not. Why shorten the life of your compressor using motor oil or hydraulic fluid to save five bucks a year? An ounce of prevention is worth a pound of cure.