I can't believe what I'm reading in this thread.
You DO NOT use any type of synthetic oil in an R12 system. Use MINERAL OIL ONLY.
Secondly it absolutely DOES matter whether you charge through the low or high side. You can charge through both sides initially after pulling the vacuum, but once you start the engine and engage the clutch, CHARGE THROUGH THE LOW SIDE ONLY. Charging through the high side while clutch is engaged can EXPLODE THE CAN IN YOUR FACE.
Third, too much oil in the system is worse than not enough. To quote Steve Brotherton; "Not enough oil wears out compressors while too much oil destroys them."
You now need to discharge the system, break all connections and thoroughly flush EVERYTHING except the compressor. Remove the compressor and dump out as much oil as you can get out then rinse some mineral oil through it.
After that reinstall the compressor and put the correct amount of MINERAL OIL by putting a little of the quantity in several components. That is if it takes six ounces, put two in the compressor, two in the condensor and two in the evaporator.
Seal everything up, THEN pull your vacuum again as you did, then charge the system.