I am not sure what kind of hydraulic or compressor fluid I need to put in my new yong heng compressor? I have read from others members here that said do not put hydraulic fluid in this compressor even though it says to use iso 46 hydraulic fluid and others said to use synthetic compressor fluid ? Others said do not put an expensive fluid in a 350.00 compressor .I want to be able to use what would be best that would protect the compressor during normal and proper use ! What should I use hydraulic or compressor? Synthetic or not ? What ever the majority is can you tell me what brand and what I should look for when buying it ?
Still confused!
- Thread starter rld1965
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Mine has been going strong for a cpl years what more can I tell ya take care of it “don’t overheat” keep oil changed, I’ve never used a single drop of purple, this is what I and others up here use 
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My two year old manual for my two year old compressor says to use ISO46 some say that the manual no longer says that but recommends something different. I have seen no proof as of yet. Someone please show me the manual that says to use something different.
I think you will find many people using many different oils in their Yong Hengs. Not because they are recommended but because they think they werq. If you can run an oil in the compressor for many hours and a for couple of years, and it seems no worse for the wear and tear and still functions well, then it is probly an acceptable oil the way that many of us look at it anyway.
But if you want to know the correct stuff to use read the manual that comes with your unit.
I forgot to put the oil back in my compressor after werqing on it one day. So I fired up my Yong Heng and topped off my 90ci tank without a drop of oil in it. Still the compressor dutifully did it's job without much of a complaint. When I realized the evil deed I had done I was more than frightened that it would never be the same after being treated so horribly. But I filled it with oil and it started right up albeit a little slow this time and it began to run just fine shortly after. It is still running fine several months later as well. I figure any oil that will protect that well deserves to be used. So I do.
I think you will find many people using many different oils in their Yong Hengs. Not because they are recommended but because they think they werq. If you can run an oil in the compressor for many hours and a for couple of years, and it seems no worse for the wear and tear and still functions well, then it is probly an acceptable oil the way that many of us look at it anyway.
But if you want to know the correct stuff to use read the manual that comes with your unit.
I forgot to put the oil back in my compressor after werqing on it one day. So I fired up my Yong Heng and topped off my 90ci tank without a drop of oil in it. Still the compressor dutifully did it's job without much of a complaint. When I realized the evil deed I had done I was more than frightened that it would never be the same after being treated so horribly. But I filled it with oil and it started right up albeit a little slow this time and it began to run just fine shortly after. It is still running fine several months later as well. I figure any oil that will protect that well deserves to be used. So I do.
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Use something that is actually rated for the pressures it will see. I use Shell corena s2 p150. My oil comes out CLEAN where my royal purple would see detonation and would turn black
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My YongHeng manual specifies ISO VG46 or AW 46 and on page 13, under the maintenance section, “recommend MOBIL 827 / 829 or equivalent”. MOBIL 827 (30W) and 829 (40W) are high pressure ester based synthetic. Mineral oil is fine for lubricating the crankshaft bearing. BUT … What can happen, as these oils are basically petroleum based, is cause dieseling (detonation) in the high pressure cylinder. If the compressor is allowed to get hot, the oil vapor is transferred to high pressure side forming carbon on valve plate and worse … detonation, blowing the compression rings out of high pressure piston. Synthetic oils are rated for higher temps and limit vaporization and carbon formation.
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As a rule, synthetic-based oils are no less prone to detonation than mineral-based oils. Detonation occurs not because of the running temperature of the compressor but because of the heat generated by the sudden compression of charge of air-oil mixture like in a diesel motor, that's why it is called dieseling. Have you ever heard of Eco or Biofuel, It's basically synthetic diesel made from vegetable oil or refined animal fat. A filter between the first and second stage would possibly be the only real way of avoiding this problem but YH only uses a half-arsed attempt to do this with the so-called cyclone separator. The best advice is to not overfill the sump.
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Your oil says that it is recommended for rotary-screw type compressors. I've got no idea what makes the oil any different for them but it is probably better to stick to something that is specific for reciprocating piston types because that's what you have.
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I found out Air Venturi oil and Kobalt at Lowes compressor oil come from the same vat. And, it costs 1/3 as much.
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Kobalt oil flash point 176 C, 287 F
https://dkist.nso.edu/sites/atst.nso.edu/files/msds/Kolbalt%20oil%2011702_MSDS.pdf
the Amsoil compressor oil flash point 262 C, 503 F degrees
https://amsoilcontent.com/ams/msds/pck.pdf
educate yourselves
Amsoil quote "The correct viscosity grade compressor oil is recommended for use in rotary screw, rotary vane, reciprocating and other compressor applications. Compatible with PAO, ester- and petroleum-based compressor oils. Not compatible with glycol- or silicone-based compressor oils."
there is a LOT of difference between mineral based oil flash point and class V synthetics
https://dkist.nso.edu/sites/atst.nso.edu/files/msds/Kolbalt%20oil%2011702_MSDS.pdf
the Amsoil compressor oil flash point 262 C, 503 F degrees
https://amsoilcontent.com/ams/msds/pck.pdf
educate yourselves
Amsoil quote "The correct viscosity grade compressor oil is recommended for use in rotary screw, rotary vane, reciprocating and other compressor applications. Compatible with PAO, ester- and petroleum-based compressor oils. Not compatible with glycol- or silicone-based compressor oils."
there is a LOT of difference between mineral based oil flash point and class V synthetics
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I have been using rotary synthetic oil for three years, works great, I’m sure the Royal purple is fine also, do not over fill and change it every 25 hrs or so, they get a lot of particulates very fast, I would also recommend changing after the first couple hrs when new, alot of break in crap in there. the key is heat boys! I wouldn’t run them over 15-20 min or over 50-55C, you are only seeing the head temp on the gauge, but when the oil gets hot, you will see a lot more second stage bypass, and smaller tank the better, for me, 30 min is the best, my 45 and 60 min work the little honker yanker pretty hard. I drop my tanks to 3k and fill to 4K, I run them more often in shorter intervals, Just how I roll for what it’s worth. 
Good luck!
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Oh and get familiar with Ali express, you will need a part here or there and plan on replacing the gauge, I have seen 5 of those crap out on different peoples units
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I use the Husky Full Synthetic compressor oil. It has a flashpoint of 460 F degrees, is priced reasonable ($6.98) and its clear so you know when its dirty. I have never had a problem. There is no need to run stupid expensive oils in these compressors. There are many things that will break before you have a lubrication related malfunction.
https://www.homedepot.com/p/Husky-16-oz-100-Full-Synthetic-Compressor-Oil-018-0083H/300135698#product-overview
https://www.homedepot.com/p/Husky-16-oz-100-Full-Synthetic-Compressor-Oil-018-0083H/300135698#product-overview
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