[Richard]

That's a good one. The technically correct way to do it is to charge the system, run it for 30 minutes, evacuate the charge, and pour the remaining oil out of the compressor. Sanden literature will tell you how much should be in the compressor. You compare that to what was in the compressor and add oil accordingly. That does not sound like a great process.


There is info on the Evans tempcon site under system oil allowances that should give you a decent estimate. I would post the link but I'm not smart enough to do that using an ipad

Here is the address http://www.evanstempcon.com/tsg_oilallowance.php

This is a great technical site for dash AC systems.