Best Penetrant to Remove Differential U-Bolts?

U bolts are cheap. The fight isnt worth $30 imho.
I bought new ones for the barracuda,i have removed my diff 6 times now, roll it in shop, set up rotisserie and pull diff and springs.
Sunday i re-assemble and roll it back into storage.

I don't disagree. Plus, you are not supposed to reuse those U-bolts. If they are tough to get off, I throw them away. If they break loose easily, I will reuse them......but again, they are supposed to be a one time use.