As mentioned above, I would try some "fog fluid" which is not oil based. I did quite a lot of research on building smoke units and most are based on a hot wire vaporising "smoke oil" of some description. These were originally based on various oil concoctions but the problem is carbon deposits build up baking on to the element causing loss of performance and overheating and breakage. With any oil based product there is also the danger of overheating and a fire.
Other than the recent trend to use ultrasonic foggers (which use plain water) most if not all commercial units tend to use a "fog fluid" which is not oil based and therefore cannot catch fire. Its generally know as "smoke oil" hence the continuing confusion but its water and glycol based so is completely harmless although I wouldn't suggest you drink a pint of it! (Unless you want to spend extensive time in the small room of the house!). Fog fluid is readily available in Maplins in the UK about £20/£25 for 5 litres but sometimes they do 1 litre bottles for much less.
Cheers
Geoff
"glycol based so is completely harmless "
I have to disagree strongly with the above, The following is from "The National Institute for Occupational Safety and Health (NIOSH)"
DESCRIPTION: Ethylene glycol is a useful industrial compound found in many consumer products, including automotive antifreeze, hydraulic brake fluids, some stamp pad inks, ballpoint pens, solvents, paints, plastics, films, and cosmetics; it also is used as a pharmaceutical vehicle. Ethylene glycol has a sweet taste and is often accidentally or intentionally ingested. Ethylene glycol is chemically broken down in the body into toxic compounds. It and its toxic byproducts first affect the central nervous system (CNS), then the heart, and finally the kidneys. Ingestion of sufficient amounts can be fatal. Ethylene glycol is odorless; odor does not provide any warning of inhalation exposure to hazardous concentrations.
We all have heard about dogs and cats being poisoned by antifreeze, it affects us too.
Regards,
Gerald.