I'm in the process of rebuilding the calipers on our '64 4/4. The pistons have been removed, everything has been cleaned and I'm ready to reassemble. Is there a grease recommended for the new seals in order to get the pistons back in, or should I just use brake fluid. The only grease that I can find that specifically mentions "caliper assembly" is silicone based, and I'm using a DOT4, non-silicone fluid. Any advice is appreciated.