Yong Heng oil changes

Looks like it could be this issue.

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This image is from a recent post on facebook PCP Compressors & Tanks, "The Good, Bad and Ugly".
 
Queequeg, I don't know the properties of hydraulic oil, but that is what the Yong Heng factory specified for use in their compressors; (AW #46 Hydraulic oil). I don't use it anymore, but I did in my first Yong Heng and for awhile in my second one. It is all speculation about what is best to use, but I suspect that just about any oil will work. the oil does not get hot in the crankcase and very little gets past the rings into the compressed air supply.
 
I bought my yong heng as a backup for my omega air charger and have been using the AW #46 in it ever since with no problems knock on wood, I've had mine 2 years now and only change the oil when it starts to turn brown, I changed it last week after filling my scba bottles several time usually from 3000 to 4500psi and the oil was still as clear and clean as when i'd changed it a couple of months ago.
 
Matt, I have seen two other posts in different forums with a similar issue. However they were not the same units - one of those posts was a unit with the single cup seal on the top of the high pressure piston. I have only read speculation on how / why it happens - nothing concrete.

I'll email you pictures I took of the manual's pages. I have to break it up into 4 emails. PM me the enail address you want it sent to.


 
I bought my yong heng as a backup for my omega air charger and have been using the AW #46 in it ever since with no problems knock on wood, I've had mine 2 years now and only change the oil when it starts to turn brown, I changed it last week after filling my scba bottles several time usually from 3000 to 4500psi and the oil was still as clear and clean as when i'd changed it a couple of months ago.


Given mine only lasted a year with only 11 hours I guess it's time to reevaluate the oil I'm using which is Royal Purple.

As far as I am aware it isn't being run hard and put away wet. Start up and shut down precautions are being done properly.

No overheating issues.

Time to try the AW#46. Which brand are you using and is it common enough to buy locally?

Thanks!