Rather than make a new thread as planned, I will just join here. When I bought the truck and later for painting, I power washed the underside of the block and frame in front, which is full of grease and spilled oil. Used a cold-water 100-110 bar (about 1500 PSI) hobby cleaner and both times I was in a hurry, so no meticulous inch by inch cleaning. The greasy parts did not seemed very different after the cleaning.
Unfortunately, I cannot get the truck to a steam cleaner or vice versa, so that is out. Does raising the pressure from 110 to 130 bar (1700 psi) with higher volume and a yet-head on the spraying lance makes makes much difference? Cannot use too much chemicals where I am, but have to get the stuff clean before continuing the restoration.