Hello Marcelino your doubts are very reasonable and very true the same I asked myself 15 years ago before devoting myself to refrigeration. I will try to be brief. When a refrigerator loses gas, it is unfailingly due to a leak, so you have to look for it and fix it. PEEROOO is not always in places accessible to the naked eye. inside has 4 or 5 meters of pipe that heats the door frame and another 13 or 14 meters of pipe where the cold is made. So if you lose that part, it can only be detected by separating the high and low pressure pipes and pressurizing the system and waiting to see which pressure drops, as that would be the puncture. They can puncture themselves by corrosion of the pipe or by accident when someone wants to defrost it with knives to take off ice. Now we go to another situation: When a system is covered either the filter or the capillary or some section of the pipe also has the same symptom as if it had leaks and if it had a compressor worn in its mechanical part with little pumping force you also go to have almost the same symptoms of lack of refrigerant but the difference is that the low pressure remains high and you have little performance in terms of temperature. The gas does not degrade or deplete or anything like that because inside the refrigerator it will last for many years until the compressor breaks or the refrigerator falls apart or a spit is punctured but in the meantime if it is not skewer must be there Clarify DO NOT DEGRADE OR SOLD ONLY SO BECAUSE YES. Let's go to something else, there are the mini losses that after giving gas lasts months or years the gas inside the refrigerator until a certain amount comes out and stops cooling again. Solutions to this problem because if the loss is large and the refrigerator is in good condition, this pipe can be replaced or risk taking gas periodically or replacing the refrigerator is subject to economic availability and repair costs. good luck