Does it smell like gas?
If so the canister is probably cracked. If you have a vacuum pump you can take it out, plug each opening and pull a vacuum on it, should hold.
Lines should be just the 3 on top.
If it's oil, I vote for Power steering.
When you fill it up, do you let the pump shut off then fill it up the filler neck? That will cause liquid gas instead of vapor to gather in the canister and saturate it.