Like the title says, my stern drive reservoir is empty and my bilge is full (of stern drive fluid). I don't see any leaks inside the engine compartment. I wrapped a paper towel around the quick connect fitting at the transom, and it stayed dry. I checked the vent screw in the stern drive, and it is full. But the level in the reservoir is still dropping. Can a seal leak in the upper unit be so bad that it leaks back through the drive shaft bellows even when the boat is sitting up in the boat house? The drive is in the full down position. Thanks.