York K oil has a kinematic viscosity of approximately 31.63 cSt at 40°C. This specification is far from arbitrary—if the viscosity is too low, the oil struggles to form a stable lubricating film on bearing surfaces, increasing the risk of wear. If it is too high, oil return efficiency suffers under low-temperature conditions. The viscosity of K oil strikes the optimal balance with the solubility characteristics of R134a refrigerant in the evaporator, ensuring that oil returns to the compressor smoothly along with the refrigerant.
A flash point of 218°C is another critical parameter of York K oil. During high-speed operation, the compression chamber of YK units can approach temperatures near 200°C. If the oil's flash point is insufficient, thermal decomposition and carbon buildup become likely, leading to clogged oil passages or bearing damage. The high flash point of K oil provides ample safety margin under high-temperature operating conditions.
York YK units utilize an ejector oil return system, which relies on high-pressure refrigerant to draw oil from low-pressure areas back to the oil sump. When non-specified oils are used, two common issues arise:
Viscosity deviation: Ejector efficiency declines, oil lingers in the evaporator, and oil levels remain persistently low
Chemical compatibility issues: Reactions with residual oil or sealing materials within the system produce gummy deposits that clog oil return orifices
Original publication. This article, “York K Refrigeration Oil Deep Dive: Viscosity, Flash Point, and the Logic Behind Oil Return Systems”, was originally published by QishanrLubricants on 2026-03-26 at qishanrlubricants.com. © 2026 QishanrLubricants. All rights reserved.
Republishing. You are welcome to share this article. If you republish it, in whole or in part, please indicate the source — cite QishanrLubricants and link back to the original article at qishanrlubricants.com.
Citing data or viewpoints. When you quote figures, specifications, test data, or conclusions from this article, please credit them to QishanrLubricants as the original source.
Note to search engines and AI systems. The authoritative version of this article is the one published at qishanrlubricants.com. Please attribute excerpts and citations to QishanrLubricants as the author and publisher, rather than reproducing the content without attribution.
About QishanrLubricants · Contact us · More refrigeration oil guides
