Do I have to add refrigerant oil the the A/C system when I recharge?
The general rule is that the automotive A/C system is a closed system, and unless oil has leaked out, there should be no reason to ‘just add oil’ every time you recharge the system. Having said that, it’s also true that components like compressor shaft seals and some ‘quick connect’ fittings will leak oil and may not even show a sign. Adding an ounce of refrigerant oil to an otherwise leak free system is not going to hurt it. Just don’t add too much because an oil overcharge can cause poor cooling problems.
