A/C compressor tm-31 oil level

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Oil is supposed to completely mix with the refrigerant and flow with it. I’m not familiar with a sight glass on a compressor, just the ones seen sometimes on top of driers or on a line fitting near the drier. Tm-31 oil either. For my Trucks 134a system, they suggest draining oil from both old and new compressors, (assume that 1 Oz. is left in each compressor) , to get an approximate idea of how much oil is needed. Then add the same amount taken from old compressor, back into the new one. Other notes claim to add 1 Oz. for any hoses that were flushed. 2-3 oz. for replacing an air drier. Another oz. or two for evaporator or any long hoses (to a bunk for instance) that were flushed or replaced. ETC. These are rough estimates for changing or flushing parts. Regardless, the total amount should be roughly 7% of the total charge. Since oils heavier than the refrigerant, when a system loses pressure, a lot of oil usually remains in the system, especially at low points. Bottom of compressor, evaporators, condensor, insides of lines, whatever. So at best it’s a big guessing game. It also assumes the oil amount was correct originally. Only way to get it perfect, is to flush or replace the whole system. That’s not realistic, unless it’s old and needed anyway. Typically evaporators and condensors can’t be flushed completely. Since they’re usually not a closed loop design. Instead they’re a header w/cross fin design, like radiators. Once contaminated, they really should be replaced. Especially condensors. They’re impossible to flush. I’ve flushed my evaporators, as much as possible, never got them totally clean. The new drier should pick up any remaining small debris, as long as its doesn’t get stuck in the orifice ( or expansion valve ) first. A bad compressor often only contaminates the high pressure hose, as debris flows out. Once high pressures lost, the flow stops. Likewise, the compressor can Lock up, and not cause any or very little debris. You can see it, and flush just the one hose, and usually be fine. Any further contamination, part needs to be flushed or parts replaced. Sounds like you’ve got it fixed good. I’m guessing you have some long hoses to the back of the Truck. Must be a big compressor too. That’s a lot of oil. Using the 7% rule, 15 oz. oil is enough for 199 oz of refrigerant. Making the total charge 214 oz. Or 13.375 lbs total. Maybe a different ratio for T-31 oil systems?? Otherwise, I’d guess you probably have plenty of oil. Surprisingly the Compressor Manufacturer’s suggestion is it’s better to have too little oil than too much. Apparently too much oil displaces refrigerant, causing the Compressor bearings to run hot, possibly shortening its Life. The compressor relies on refrigerant to keep itself cool. Good Luck. Sounds like it’s fixed. Maybe the old Compressor was weak, and not enough pressure to keep the oil mixed? I don’t know why you would see oil pooling otherwise. I’m not a refrigeration mechanic, just changed a lot of them on my Trucks over the last 20 yrs. It’s very interesting stuff. Learn something new every time.