Estimating & adding oil after a major manifold gauge leak/malfunction

[ToxicBard]

I had an A/C system that had been working fine for years with no leaks or anything. I decided to buy a manifold gauge set and check the pressures in both of my vehicles so that I'd know in advance if I had problems on the horizon. I left it running with the gauges connected for 5-10 minutes while I walked inside to google how I should be interperting my readings (low side low, high side within range). By the time I came out, I noted that the high-side hose on the manifold gauge had split in half (due to poor design and a manufacturer defect) and my system had completely depressurized itself from the high-side hose, most likely very quickly.

I'm assuming that, since the oil is suspended in the refrigerant, and due to the speed with which the system drained itself, I lost most, if not all, of my oil, and thus should be re-adding the full amount (8.75 oz). I see all over the place that if you have a minor leak, you shouldn't add oil, but this was not a minor leak.

I've spent the past few weeks replacing my expansion valve, evaporator core, and dryer. I added 2 oz of PAG oil to the new evaporator, 1 oz to the new dryer, and I was planning on adding 4-5 oz via an oil charging can. Immediately after installing the new dryer, I pulled a vacuum for over an hour and charged it with 1 can of straight r134a (no additives).

When I tried using the PAG can, it kind of fizzed and acted strange: I measured 4.7 oz of displacement from the can, but I'm unsure as to how much of that went into the system, and how much of it just got stuck in the hose and drained out of the manifold gauge hose as I disconnected (there was at least some that did). I learned in the process that those cans are crap and I'd be better off adding proper oil directly to the components in the future.

What I'm trying to figure out, and haven't been able to find answers to with extensive googling, is:
-Am I correct in assuming that I probably lost most, if not all, of my oil when the high-side manifold hose split open?
-I gather that there's no way to know how much oil is in the system without doing a proper, extensive flush. However, are there at least some kind of hints, clues, warning signs, etc, to suggest when I've got too much or too little oil to the point of causing problems? In other words, if I continue to charge my system, get the pressures within range, the air blowing cold, and move on with life, then how likely am I to encounter problems, and would there be some way of detecting them before my compressor eventually fails?

[Cusser]

I had an A/C system that had been working fine for years with no leaks or anything. I decided to buy a manifold gauge set and check the pressures in both of my vehicles so that I'd know in advance if I had problems on the horizon.

I'm still in shock about this part. One evaluates an AC system by knowing that it's putting out cold air and the user is comfortable. You attached gauge set to a system that was operating well, and created your own issue.

Agree that you need to get the oil to the right level, but I don't know how to estimate that for something so catastrophic.