Bought rebuilt np241dhd transfer case from Napa. Rebuild tag specified 30w non detergent oil. I had Napa call rebuilder to confirm this. Rebuilder said due to sycronizers that were used 30w needs to be used. Manufacture calls for dextron lll +4. They also painted the case grey, will this affect cooling ability. Does anybody else find this strange. this rebuild makes me feel uneasy.