On Mon, 3 Mar 2008 15:24:50 -0800, (Dave Platt)
wrote:

In article 3k%yj.13936$ES.918@trnddc05,
James Sweet wrote:

Mineral oil.

Isn't that primarily what motor oil is? I can get small bottles of clear
mineral oil at the pharmacy, but it would cost a fortune to get the gallon
or two I need.

Motor oil usually contains a complex series of additives, which might
or might not be compatible with electrical applications.

I certainly wouldn't want to buy mineral oil in quantity in the sort
of pint bottles you find at a pharmacy... too expensive that way. The
least expensive place to get pure mineral oil is probably a veterinary
supply store. It's used as a laxative for animals. The cheapest
online price I see in Google is under $11/gallon, which is reasonably
competitive with motor oil.

Food-grade and animal-grade mineral oil would lack the possible
toxicity issues which might come with the additives in motor oil.

If you want to go cheaper, get hydraulic oil. It is about 10 wt (bit
thinner than 30 motor oil) but has virtually no additives.