Best solvent for soaking caked on grease

We purchase in drums
Yes. However most are microemulsions where the d-limonene content is less than 5% solubilized into water and surfactants. This is not what you are looking for. D-limonene is actually flammable with a flash of less than 120F. You can light your charcoal with it or melt asphalt.

This is by far the coolest thing I'm going read today! Always learning something new from you.
If you can deal with the overwhelming woodsy smell Pinesol diluted 50/50 with water is worth trying. A lot cheaper than brake cleaner. I learned this from the advrider motorcycle forum. I’ve run into those hard as concrete dried vintage grease problems before. It is some tough stuff.
Appreciate the replies everyone. I've tried easy off, and it works pretty decent. But not feasible for lots of smaller parts and requires lots of scraping and wire brushing afterwards, and the fumes mess with my asthma. I've read about Lye and TSP soaks with hot water, the only problem is that I don't have water at my shop yet to rinse parts off, or any burners or pots to heat them in.

I'm mainly interested in the 5 gal buckets of brake cleaner or other solvents at the moment, I need something I can dunk the parts into, let sit for a few days, pull them out, then rinse them off with my parts washer. So far the Chem dip has been the only thing that's fit this criteria, but it's around $300 for a 5 gal bucket.

Does anyone has any experience with bulk brake cleaner that isn't in an aerosol can? Does it evaporate the same? Clean the same? Etc.

99% of the parts are cast iron or steel. Some brass, but that's all being cleaned by hand.
BERRYMAN'S makes a 1gallon can and a 5 gallon bucket.

There are several excellent solvents for grease... including carbon tetrachloride, methyl ethyl ketone, perchloroethylene, trichlorethylenexylene or if you wanted to go "old school"... plain old toluene.

But you asked for the "best" degreaser, so IMHO:

Carbon tetrachloride