I know someone who insists on using new, unused motor oil to burn garden waste (in a garden area). Somehow, I'm pretty sure this can be bad for the garden and/or people's health who eat the stuff grown in the garden.

Can you please tell me what, if anything, is wrong with this (besides risk of burns and fire spreading)?

Also, can you tell me healthy alternatives that I can suggest that would work just as well? (If unused motor oil indeed makes the ashes unhealthy for the garden, I mean.)

  • can you describe the garden waste? Is it woody, herbaceous, full of moisture...?
    – Nic
    Commented Mar 21, 2016 at 22:56
  • Oh, yes. I was just about to do that. The waste is primarily tree branches. Commented Mar 22, 2016 at 0:04
  • 4
    New motor oil contains ash dispersants and other additives make this a kind of dumb idea and used motor oil is full of carcinogens and heavy metals. Burning perfectly compostable garden waste? Pfft! Commented Mar 22, 2016 at 4:33
  • I recently found this link, which basically says what new motor oil contains (although ingredients are variable, apparently; so, getting an analysis of its exact effects is going to be pretty much impossible): bobistheoilguy.com/whats-in-your-motor-oil Commented Mar 24, 2016 at 19:26
  • @FiascoLabs While I concur that using motor oil for burning (or anything, really) is very bad, it should be noted that there are practical reasons to burn garden waste without motor oil, and composting is not always anything like an option. It would require a lot of land and/or equipment to compost those trees. It seems that just lighting the fire with regular firewood designed for burning is an effective way for the person to burn the branches, however fresh the branches are. Just getting a strong, sustained fire seems to be the need. Commented Mar 24, 2016 at 19:37

4 Answers 4


Composting is a pretty healthy alternative. Here in the UK you can buy electric garden shredders for under £100, allowing you to compost almost anything. In the long run you'll save on buying motor oil.

I've also seen people woodburning stoves by dousing in cooking oil, if it's edible then the residues left should be safe enough.


Lot's of issues

Don't use it for anything, it's an environmental hazard.

Just get rid of it in the least impactful way.

Used motor oil has a plethora of bad chemicals and compounds in it that eliminate for another use once it has been inside your engine for an extended period of time.

Aside from the hydrocarbons

  • lead

  • phosphorous

  • berium

  • zinc

  • bromine

  • aluminum

  • arsenic

  • calcium

  • chromium

  • copper

  • iron

  • magnesium

  • manganese

  • potassium

  • silicon

  • sodium

  • tin

  • toluene

  • benzene

  • xylene

  • ethylbenzene

Here's a link from the CDC.

  • The question clearly states "new, unused motor oil" - which is a peculiar choice .vs. diesel fuel or kerosene, both of which burn better than motor oil without being gasoline, but USED motor oil was not part of the question.
    – Ecnerwal
    Commented Jan 29, 2018 at 2:52

A lot of commercial hothouses burn used motor oil - which is worse than new stuff.

If done correctly its quite safe to eat the fruits produced, but its not great for the environment.

There are quite a few bad things in it - in a commercial greenhouse heater these are ducted out the hothouse. That said if the units are not looked after properly, they can leak contaminants into the house which can hurt the plants. Be especially aware of carbon monoxide - which can silently kill people working in it.

Note: that the air fuel ratio is important in reducing the amount of contaminants released into the atmosphere.

In some places oil can also be used to heat outdoor areas like orchards - again, not great for the environment, but commonly done commercially to save crops from frost - but more so in yesteryear I think.


What! If the smoke is sufficient call the fire brigade. I'm sure they will put this person straight on this. The noxious fumes are deeply unpleasant and unhealthy, releasing all sorts of exhaust fumes and pollutants Into the atmosphere. (we are constantly being told to reduce use of fuels for global warming etc. Do you have an environmental health dept you could contact? Local authority, or local bylaws to prevent this? It's they who should respond to this nuisance. If they want to burn rubbish, why do they need an accelerant of any description. It's not that difficult to start a fire with some kindling and a couple of matches. If you're attached to this person, it would be a difficult situation to remedy without causing a lot of angst.

  • Are you saying it's illegal? (This is in the USA.) Most of the things I've found myself about toxins from burning them were about used motor oil. This is new. So, I need to get information on new oil, if I'm to convince the person properly. But, if it's illegal, that will probably be enough to convince the person. Commented Mar 22, 2016 at 0:12
  • It looks like whether it's legal may depend on the county and maybe the state, too. It's illegal some places, but not everywhere. Commented Mar 22, 2016 at 0:17
  • Hazardous waste is illegal to burn in the area, but I need proof that new, unused oil would be hazardous to burn (or not). Used motor oil is definitely hazardous waste, though. Commented Mar 22, 2016 at 0:34
  • Okay, I found this link: google.com/… Which was sufficient to convince the person it was hazardous, and not to burn with it. So, it's all settled. Thanks! Commented Mar 22, 2016 at 0:50
  • Truth be told, I'm not 100% sure that burning it is hazardous, but the oil itself is hazardous without burning it (though not the same as used motor oil). I imagine burning it wouldn't be healthy. Commented Mar 22, 2016 at 0:57

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