Yongheng Compressor Break In? Compressor Oil?

I like the Nuvair 800 because it is designed specifically for extreme pressure compressors "with the latest technology". It costs a bit more but it doesn't take much to change the oil in my single cylinder. A very high flashpoint compressor oil makes me a little more at ease because of the temp's and pressures involved. When you think about it too much these setups are a bit scary! I agree with Stefanjan about the no load breakin and frequent oil changes in the very beginning as you will see when checking the oil color. Bill.
 
I have a Yong Heng compressor and first ran it with Amsoil SAE 30 for about 1 hour (maybe less-I did not time) while topping my 2 SCUBA tanks from 2000psi to 3000psi. I then moved the air from the SCUBA tanks to my new SCBA 4500psi tank and then topped the SCBA tank to 3600psi using the Yong Heng. I then changed the oil in the compressor and filled with Royal Purple Compressor Oil. I was surprised that the drained oil looked very clean. I question whether the compressor oil is any better than synthetic engine oil. I know your question is in regard to "breakin." I suppose my compressor has done the "breakin" phase and it works flawlessly!
 
I couldn't find any Royal Purple or Amsoil on a Sunday, but Home Depot had house-brand "heavy duty synthetic compressor oil". I figured it's prolly good enough for break in, meanwhile I'll try to find Royal Purple.

Running wide open my temperature climbs to 50C within 2-3 minutes, which seems kinda fast. So far I've run it up to 50C twice and let it cool down. I confirmed there's good flow coming out the water tube, and the tubing is not hot to the touch, but the 1st stage head is definitely warm to the touch so the thermocouple works.
 
I couldn't find any Royal Purple or Amsoil on a Sunday, but Home Depot had house-brand "heavy duty synthetic compressor oil". I figured it's prolly good enough for break in, meanwhile I'll try to find Royal Purple.

Running wide open my temperature climbs to 50C within 2-3 minutes, which seems kinda fast. So far I've run it up to 50C twice and let it cool down. I confirmed there's good flow coming out the water tube, and the tubing is not hot to the touch, but the 1st stage head is definitely warm to the touch so the thermocouple works.

Your temperature is normal. It will climb very fast until it levels off, some ware between 50 and 65 depending on your ambient temperature. Low friction oil is not recommended for breaking in because it prevents wear. Breaking or wearing in requires wear. As for requiring synthetic oil for these things, I believe is a load of wank. Any mineral-based compressor specific oil should be more than adequate to lube the big end of these crude and basic designed pumps. I don't think synthetic oils are any less prone to dieseling than mineral oils. The advantage of using synthetic over mineral is only of use in modern tight tolerance machines operating in extreme temperatures in conditions like racing. Some of these guys that run their pumps in for ten minutes and change the oil after every fill of their gun are fooling themselves if they think it will prolong the lives of the thing. I am using compressor oil that I bought from a large auto and machine company it has an ISO rating of 68 and rated for all piston type compressors. It was the only compressor oil that they keep in stock because it's the only one that there is demand for. I changed the oil after the first hour and a half and I probably won't change it again because I expect the motor to burn out first. To the guys that change their oil after every fill. Do you change the oil in your car after every trip to the corner store? It won't do any harm, it's just pure overkill.
 
As for requiring synthetic oil for these things, I believe is a load of wank. Any mineral-based compressor specific oil should be more than adequate to lube the big end of these crude and basic designed pumps. I don't think synthetic oils are any less prone to dieseling than mineral oils.

From Smith and Allen compressor oils...

Airtech RX compressor fluids are a range of high quality fully synthetic ester based fluids, which are recognised to offer superior performance over mineral based lubricants in reciprocating air compressors. These fluids harness the latest additive technology to provide the highest possible performance in all operating conditions, with extremely low volatility and foaming tendency. The higher auto-ignition temperature of these fluids inhibits deposits from forming, allowing for safe, reliable operation and maximum safety in air lines. Airtech RX fluids also offer outstanding wear and rust protection, as well as exceptional oxidative and thermal stability even at high working temperatures and pressures; they also exhibit excellent water separation characteristics, therefore preventing accelerated corrosion and facilitating separation from condensate.
 
Update: I ran my compressor for a little over two hours with synthetic compressor oil (Home Depot brand--haven't gotten around to getting the Royal Purple) which included running "open" for about 10 minutes, and filling my 44cf scba to about 3800 psi. I didn't go higher in pressure, because the original quick disconnect fitting on the compressor developed a leak and barfed up a broken o-ring. 

I drained the oil while waiting for replacement parts. It had turned pretty dark in the last few minutes of high pressure operation. I've kept the temperature below 60C.

Yesterday I repaired the fill hose and topped off my tank. It took about 20 minutes to go from 3200 psi to 4500 psi, and the compressor got up to 58C. I've followed others here with using frozen bottles of water in the cooling water, and that seemed to make a difference, as just running regular water I could only get about 10 minutes before hitting 60C.

Pretty amazing performance for a $300 compressor.

I'm assembling the parts for a moisture separator and molecular sieve, but need to modify some NPT fittings to M10x1 so I can plumb everything up.