Hi Lorenz,
I usually hit it with generous amounts of degreaser, let it do its thing and then go nuts with the pressure washer.
However, I've just sent some alloy bits away for vapour/aqua blasting, including a head. I'll post results in a few days when I collect them, but from what I've seen, it's a great process.
Last edited by Mystyler; 17/05/20 10:30 PM. Reason: Grammar.