I like that Castrol degreaser also. It all works better if you spend a LOT of time scraping 1st. Start with a big old screwdriver or chisel, and work down to smaller tools. I finish off the small cracks, corners, holes, seams with a dental pick.

1962 Fleetside 4spd 235 w/O.D. posi 3:90
In the Stovebolt Gallery
1990 Subaru Legacy Wagon AWD 2.2 5sp
2013 Ram Tradesman C/V
My Webshot Photos]