As most all of us will admit, our MGs occasionally leak a little oil (mine does). Some people spend boat-loads of money trying to stop it, while others just joke about it, referring to it as ‘marking their territory’, or it being ‘automatic rust inhibitor’ streaming down the undercarriage of their car. Some joke that ‘If an MG doesn’t leak, it means it’s out of oil’, or 'I never have to change the oil in my car because I’m always adding more in the top as it drips out the bottom.' At any rate, we’re frequently out there in the garage with our rags or paper towels wiping up the spots, or cleaning up the tools after an oil change. But what should you do with those oily rags or paper towels? Is it OK to just throw them in the trash barrel? Some say ‘No’, it’s dangerous because of spontaneous combustion. Is that something I should be worried about? I’ve never seen it, or heard of anybody having it.

Is it real?
Spontaneous combustion, or auto-ignition, is definitely real. The Chinese wrote about it as early as 290 AD. There are videos on YouTube demonstrating how linseed oil-soaked rags can spontaneously combust in as little as three hours. Just a few day ago, a large pile of yard waste and compost at a recycling center in my neighborhood spontaneously caught fire. Grain elevators catch on fire. The 1937 Fox studios vault fire was caused by spontaneously combusting nitrate film. It’s real.

How Does it Happen?
It happens when there’s an increase in temperature due to exothermic internal reactions, like oxidation or fermentation, followed by thermal runaway, self heating, which leads to more heating, which rapidly accelerates to high temperatures, and finally auto-ignition. It can happen in a matter of a few hours, or as long as a few weeks. It happens when heat gets generated and has no way to escape, like in a pile of rags.

What Can You do About It?
Experts talk about disposing of oily rags professionally, but how is that feasible for amateurs like us? You can’t stop what you’re doing every time you have an oily rag to dispose of. We all know fire requires three elements: heat, fuel and oxygen. You can buy flame-retardant canisters that seal off oxygen and contain any flames, but they’re expensive. So here’s what I’ve decided I can do to minimize the problem. I want to eliminate the heat and give any heat that might get generated the opportunity to escape.

I’ve put a small piece of cardboard on the floor behind my MG, by my garage door, furthest from any heat sources like furnaces or hot water heaters, closest to fresh air to dry them out, and not in direct sunlight. As oily rags or paper towels need to be thrown away, I’ll spread them out on the cardboard. That’ll give the oil a chance to dry without trapping any heat. When the cardboard gets full, on a neighborhood trash pickup day, I’ll take a kitchen trash bag, put all the rags and paper towels (which have hopefully dried out some) in it, put it in the trash barrel, and then take the trash barrel straight to the street. The EPA does not regulate oily rags as a hazardous waste, as long as the rags do not have any free-flowing oil and are free of any other hazardous contaminants. If the oil drips off of the rags or paper towels, they are considered to contain free liquids and must be managed as used oil. You may want to check with your city on the Disposal of Hazardous Waste.

No, I’ve never seen it happen (except on YouTube). Maybe I worry too much. But even if the chances are very slim, IF it happened, the consequences could be very catastrophic. Why not put just a little effort into trying to keep it from happening. Maybe I’ll sleep better at night.

WARNING: Never attempt to launder and reuse rags that have been saturated with oily materials. Petroleum distillates and oil-based finishes contain resins that harden into the fabric as the liquids evaporate, and these toxic resins can be liberated and enter the drain system if you wash the rags.

~~Denny Hale      

Editor Note:/b> Article by Denny Hale reprinted from the Kansas City MG Post, newsletter of the Kansas City MG Car Club Vol:41 Issue:3