John, as you can see below, removing the compressor to drain it (no drain at the bottom) and measure the amount of oil is not an option unless it became a do or die situation.
This is apparently official Sanden info. My compressor is a SD-508 (why I didn't get the SD709 one is beyond me - same price - New Sanden Style 709 V- Belt Double Groove - Compressors
6.8.1 Oil Flow Theory
• Compressor lubrication occurs as the oil which circulates with the refrigerant passes
through the compressor crankcase during operation. The Sanden SD series
compressor achieves optimal durability and cooling performance when oil circulates
through the system at a ratio of 3.3% to 8% oil to refrigerant. Excess oil can act as an
insulator limiting heat transfer in the evaporator and condenser, while too little oil can
negatively affect durability.
• Oil will collect in low pressure cool components (evaporator, accumulator and suction
hose) of the refrigerant loop. For example a long suction hose which sags can collect
several ounces thus reducing overall oil circulation ratio.
6.8.2 Oil Charging
18.104.22.168 Passenger Car, Light Duty Truck Single Evaporator
Refrigerant charges 24oz (680g) to 40oz (1133g)
• 135cc oil TXV systems
• 240 cc oil in orifice tube systems
Now, do I have a TXV or oil in orifice tube system?
And...even if I drained the compressor, how much oil is in the rest of the system? And...how many ounces are there in two 18" diameter puddles on smooth concrete?
Also...I've run the vacuum pump three times. How much oil does that remove or is the oil heavy enough that it doesn't get sucked out?
I'll admit I'm fairly seriously thinking of getting the SD-507 compressor, knowing it will be a direct bolt on...and not have to worry about how much oil is in the system.
As it is, if I have a TVX system and going by the 36 oz. figure as the capacity of the system, I'd need 4.5 oz. of oil. I've added two oz. Perhaps another ounce? I was told that the oil plays a big part in cooling the system, providing you don't overdue it.
I've confirmed that the + wire from the pressure switch goes directly to the compressor clutch. Since the ground wire goes to the relay, I'm assuming the + wire then doesn't need to?