Have you checked the little screen filter where the hose goes into the tank?
Sometimes that gets gunked up and can cause a back-up that looks like a leak around the grommet.
If you've already got a new hose and grommet, just make sure everything is super clean when you put it back together.
But if it's still leaking after all that, there's a chance the plastic tank itself is cracked where the grommet sits.
It's hard to see the crack sometimes until you've got it all apart.. in that case, you might need a new oil tank housing.
