What effect does refrigerant oil in a hose have when using a manifold gauge set?

In the context of using a manifold gauge set, refrigerant oil present in a hose does not significantly affect the pressure readings on the gauge. The reason for this is that gauge readings are based primarily on the pressure of the refrigerant gas itself, rather than the presence of oil within the hose.

As the refrigerant moves through the system, it carries oil with it, but this oil does not alter the pressure readings in a way that would lead to an increase or decrease in the displayed values on the gauges. The gauges are designed to measure the pressure exerted by the gas, and since refrigerant and oil coexist in the system without changing the fundamental properties of the gas, the readings remain accurate and consistent.

If the oil were to somehow completely obstruct the flow or cause a blockage, it might affect the operation of the system, but during normal operation and when taking pressure readings with the manifold gauge set, the presence of oil itself is not influential. This is why the readings on the gauges are not affected by the refrigerant oil in the hoses.