Not a suggestion, just a quick on subject story. We have many many horse shoes in the barn from 40 years of always having a few shod horses on the place. Cleaning old rusty, dirty shoes is a pain. Little bro needed a few recently for a project. So happens I had a bag of H2SO4 in one of those plastic pouches you used to get when you bought a dry, 12v battery. Put a couple dozen old shoes in a HDPE five gallon bucket (hydraulic fluid bucket) added about 3 gallons of water, put on long rubber gloves and face shield then slowly poured acid into the water (NEVER the other way). It bubbled and rolled a bit, in about 30 minutes I pulled the shoes out and they looked new. Now, not recommending this for an engine but old battery acid (this was new acid) when handled with all due care will eat rust like candy. Proceed at your own risk. Only do this outside.
RonR
