Where do you add transmission fluid on a Cadillac Catera?
The 4L30E transmission, like their BMW (92-98 4L30E) conterparts are a totally sealed unit. The service hole to check the fluid is also the where you add fluid. This sealed unit is filled like a manual tranmission, thru the service/check hole. be patient when doing this to make sure you have adequate amount of fluid in. when it takes no more and slightly dribbles out of the service hole then it is full.