[Foley]

I think that might be a good option. I like a 50/50 ATF/diesel mix, or all ATF in those cylinders. Get the large nut on there like you say, and using a big, 3/4" drive impact wrench, give it a 5 second blast with the wrench about once or twice a day. It's not so much the torque will break it loose at first, it's the combination of the torque and more important, the vibration from the wrench that will help the penetration.