Castrol Degreaser works very well for this, along with what has been suggested. Let it soak for while, scrub some, spray more cleaner, soak, scrub, and when you thinnk you got it all, do it one more time. Then get to a car wash or power washer, and go at it. Garden hose works with a spray nozzel, just not as good as a power washer.
Go rent a 3500 psi unit and hit the frame while you have it.
Joe
