[bigblock (OP)]

I recently read an article that claims an aluminum drum full of motor oil with a zinc rod suspended inside will produce heat for years. Is this a hoax or is there some truth to this?

[lightarrow]

First of all, "will produce heat for years" says nothing if it's not specified "how much" heat. Even a grain of sand will produce "heat for years" if put in a colder environment, since it never reaches *exactly* the same temperature of the environment (even if it reaches quickly a temperature so close to it that you won't be able to measure the difference and the heat generated will be close to zero as well).
Second, it seems a hoax.

[RD]

The description sounds a bit like a battery ...

 [ Invalid Attachment ]
http://www.arizonaenergy.org/AltEnergyClub/homemade%20batteries.pdf

but pure mineral "motor" oil wouldn't function as an electrolyte, as it's an insulator ... https://en.wikipedia.org/wiki/Transformer_oil

[lightarrow]

http://www.arizonaenergy.org/AltEnergyClub/homemade%20batteries.pdf

<<But this will not be enough amperage to do anything with so what you must do is add many cells together in series...>>
Probably in parallel it's better  [].

[damocles]

The description sounds a bit like a battery ...

 [ Invalid Attachment ]
http://www.arizonaenergy.org/AltEnergyClub/homemade%20batteries.pdf

but pure mineral "motor" oil wouldn't function as an electrolyte, as it's an insulator ... https://en.wikipedia.org/wiki/Transformer_oil

That is also a pretty good description of a hoax -- HCl is a fairly poor solvent for a polymer coating, and a reasonably good solvent for fresh aluminium surface. The hobbyist who tries to follow these directions is likely to finish up with no cathode! The result will be, of course, preservation of the secret of whether the cell does work or not

[RD]

... The result will be, of course, preservation of the secret of whether the cell does work or not

I suspect the bit about soldering to aluminium is incorrect too. But nevertheless apparently the copper-coke-can batteries do work ...

[ jump to 8min 30sec ]

[ an abrasive was used to remove the varnish from inside the cans rather than a chemical ]

The coke-can-battery may actually be an Aluminium-air battery ... https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery