Back during the BP oil spill I got sent down to help with the cleanup and they explained the different types to us but that was all raw oil instead of refined fuel oil. The low sulfur was supposed to just be to satisfy the EPA and it increased the cost due to needing more refinement.

When I worked construction the owner kept his tanks there and they sprung a hole but that was because anytime it rained the water would just bead and sit on the bottom. The next tank he got was a brand new one and I welded a "skirt" on it halfway down all the way around so the water would run off instead of holding on underneath. We also put it higher off the concrete so the humidity wouldn't rust it. As far as I know it still works fine. He hasn't called to complain about it yet!