[dsfnctn]

I have tried to understand the function of the aux thermostat on a 78 911 and need a bit of help to fully understand whats going on. I seem to be having more of my share of cleaning up oil in the last few months.
It started when my 3.0 race car with a center mounted B&B cooler got lowered and then the rear tire wore thru the oil line. When I replaced the oil line and started it up the front cooler blew. My friend told me about a radiator shop so I had it fixed.. When I reinstalled it and went to start it up the cooler blew again. I changed the whole system to a Carrera cooler and a 964 cooler. Started it up again and the 964 blew. Well I just had to keep messing with it and took out the thermostat and it seemed to opperate fine. I bypassed the 964 cooler and started it up and now blew the carrera cooler.
Clean up Isle 3 again.
SOoooo, it looks like the thermostat opens on the return side but somewhere in the system I have to much pressure. The engine oil gauge looked fine and all the last blow up happened while the car was ideling low and cold. Also it just sounds wierd by the tank hose area like smething is restricted. anyone got any ideas?
Thanks for your time