Refigerator won't get colder

I can't wait until they develop a multi meter with a calculator on it displaying RH% and PT chart saturation temps. Hook ups for refrigerant line temps with automatic conversion for which ever refrigerant. A pressure port to compare actual system pressure and a sniffer. One tool like this might cost more than your box. What do you want to glean from your comment? If it is failing to achieve at least 5F in the freezing compartment you have a problem. I honestly think the ester oils break apart before 250F more like 160F but that is my educated guess. Maybe in a lab environment they can increase its withstanding drastically but in the home after running several hours ( warranties should go off run time) its always different data. If your compressor is running hot maybe they should have used PAG instead. What goes wrong with car AC? Think how much water comes out the tail pipe in your summer months. Your refrigerator often uses the same refrigerant but not the same oil as your car. Additives? Never really used them. I always just used the exact oil charge by ordering it through the manufacture. How do you do that? You replace the compressor. Of course you can sucker down and replace the drier and add a suction drier too. If you do this make sure you get the driers with bleeders for ease in service. On the new compressor put in a valve before the drier on the liquid line and suction. This way you can change the driers easier in the future without the need for a pincher tool or a process adaptor kit. I could never understand that process stub... makes a hellofalot more sense to use valves. The cost is got to be about 10dollars more!! And well worth it! That's the difference in a warranty repair. You don't always get what you pay for - sometimes, if a technician enjoys his work and takes pride in design he'll give you not only a fix but a repair worth more than what you paid for in the beginning.