Review on AUTOOL 9PCS refrigerant oil checker analyzer tester for AC systems compatible with R134a/R1234yf refrigerants by David Sidman

This product proves absolutely nothing about the condition of the oil in your HVAC system. How much oil the filter captures is directly related to the pressure in the air conditioning system and the location of the low pressure control port on your vehicle. Depending on whether the air conditioning is running or not, the outside temperature and the design of your vehicle's air conditioning system, you will receive completely different readings. Some systems operate at low pressures as low as 35psi, regardless of temperature, while others operate at higher pressures as temperatures rise. The level of pressure will supply this filter with more or less oil and in no way reflects the amount of oil in the system. You will literally overwhelm your system if you trust this product. The only way to ensure that the oil in the air conditioner is correct is to drain the system, drain the oil from the components and flush the entire system with solvent before adding the correct measured amount of oil.