The last owner decided it would be a good idea to put stop leak into the coolant, as a result the oil cooler is completely blocked, would ultrasonic cleaning unblock the cooler. I am not sure it would. I have been thinking of replacing it with a oil/air cooler and sandwich plate from ebay. These need some type of thermostat, I was thinking of using a solenoid valve and a temp sensor to switch the valve when the oil got to temp. Or just running without an oil cooler since it's coming into autumn now. Which option do you guys think would be best? Has anyone used a sandwich plate? Do they replace the OEM cooler or sit on top?