Milky and grey you've got water in the oil. That water is breaking it down and could be wearing out the engine causing the grey. If it was mine I'd be considering pulling the motor to have the block checked. If it's very grey or slight copper I'd pull the engine just to replace the bearings. It can be done in the truck but it's harder. Have the deck checked for being straight and magnafluxed for cracks. I'd be worried about a warped deck or a crack. I think it's odd that the machine shop cut the head. They don't usually do that. Some shops bolt em to a hot table and straighten them out since most alum. heads have low enough tollerances they can't be machined. Not every shop has that kind of equipment tho. It's possible it was minor warp.