So i picked up 2 free 55gal blue food grade barrels today. They came from a bakery, and contained a Release Agent (Soy Oil & Mineral Oil - Called the Mfg.).

I rinsed 2 times with about 25 gal of water & Dawn dish soap - 1/2 bottle so far. Then filled both with water & baking soda. Still see a little oil on the water.

Was going to let that sit for a day or 2, and then do 1 more soap rinse.

What else would you recommend? White Vinager?

Good luck getting that oil out.

Does the entire top open or are there just bung holes?

We use rubbing alcohol to clean gas cans of old fuel when rotating. Might help break it off the sides.

Other then that you will probably need to powerwash the heck out of it over and over again.

If you are storing wanter you might be farther ahead with virgin barrels.

I've washed them out with dawn dish washing soap, though I didn't use that much! We filled them about 1/3 of the way and then rolled them around for about 30 minutes.

Rinsed them the same way 3 times and then stood them up and filled them to over flowing. Soap and oil are lighter than water so they will float to the top and out thru the bung hole.

Turn them upside down and spray the inside for several minutes and let the water run out. It will bring the balance of the oil out.

I let some of my 55 gal drums develop algae from sittin outside (emptied before a move and NOT re-filled - OOps!) under direct sunlight for a few years. Here's what I did.

Use a non-scented Clorine Bleach. It does wonders AND it sanitizes the barrels to boot.

Use your own judgement on how much of it you use to clean em. It doesn't take a lot of clorine to do the job. I simply poured about half cup into them, added water (enough but not a lot) to swish out the barrels. I let em sit for a while after rollin em around. Then I rinsed em with clean water and refilled em. Good to go!

And JIC - I have a Berkey "Light" if I have to "filter" any water at all.

I think i got out 99.9% of the oil that was left. When i had them filled full, i could still see just a haze of oil on the water, so i just kept overfilling a few times.

Seems to have worked. They don't really smell like oil on the inside. I will do a clorine rinse before i use them.

And they have just the Bung's. Lids are part of the drum.