In preparation for this upcoming boating season, I drained the lower unit gear oil from my Honda 130 outboard. The old gear oil looked ok. I injected oil into the bottom hole of the lower unit until it came out of the top hole. When I plugged the top hole, gear oil started to leak out of the water intake area. Do Hondas have a pressure release valve or do I have a compromised gasket? The lower unit is only 2 years old and hasn't impacted on anything. Any thoughts on what might be going on??