Sorry, it is indeed Ester. I scanned the text quickly and saw the 100 weight indicated and assumed that it was Ester. Since only one weight is available with Ester, it is usually not indicated. When the weight IS indicated it usually means PAG.
That said, the common thing you hear is that Ester is "compatible" with R12. By compatible, that means that if there is a small amount in a system it will not hurt anything. To have such a large quantity in an R12 system is not a good thing.
That is not the worst of it however. The problem with the system is that adding 5 ounces to a system that was nearly full of oil has an EXTREMELY overfilled system.
As I quoted from Steve; "too much oil destroys compressors, not enough wears them out."
This system should be thoroughly flushed, filter drier replaced, the correct amount of MINERAL oil added, evacuated and recharged.