I recently heard an urban legend-like story about a guy in a developing country who decided engine oil was too expensive and so used some vegetable oil instead. The story says the car ran for some time and then it's engine got broken and required complete overhaul so that guy wasted much more than what he saved on oil.

I'm not a car owner, so I'm really curious - what's the worst thing that can typically happen if some unsuitable oil is used instead of engine oil?

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    Maybe this is one for Mythbusters? dsc.discovery.com/tv/mythbusters (Don't think they've done this specifically; Obviously, I think the vegetable oil work for a day if you're lucky, but it'd be cool to see them break it down on what specifically happens...
    – NSGod
    Commented Apr 14, 2011 at 1:10
  • It's certainly an odd myth since vegetable oil is usually much more expensive than motor oil Commented Jul 13, 2016 at 14:38
  • @DeanMacGregor That depends on location. Somewhere where vegetable oil is manufactured locally and motor oil is imported the latter can easily be more expensive.
    – sharptooth
    Commented Jul 14, 2016 at 10:37
  • @sharptooth actually I stand corrected. I was thinking of what I pay for olive oil. I just checked walmart and their cheapest veg oil is cheaper than their cheapest motor oil by volume. Oops. Commented Jul 14, 2016 at 12:56
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6 Answers 6


Many things can (and most certainly will) happen, such as: Engine seizure, pistons stuck in cylinders, broken crankshaft, broken conrods (causing holes in the engine block), damaged camshafts, worn out bearings, etc. So, always use the appropriate oil if you care about your car.


The worst thing that can happen is that you can destroy your vehicle. Your vehicle is designed to use some very specific lubrication, and using something other than what's specified can be detrimental.

If the lubricant cannot withstand high temperatures, you could gunk up your engine and require a rebuild.

  • What will happen to the engine more specifically?
    – sharptooth
    Commented Apr 13, 2011 at 7:22

The oil in the crankshaft is in contact with air and gasoline fumes. If you used an oil with an ignition point as low as the engine temperature, it would probably start a fire in there.

I'm not sure how vigorous the fire would be (that likely depends on the air supply, which probably varies between engines), but it would eventually deplete the oil, cover the crankshaft in residue, and destroy the headgasket.

That said, there are a lot of kinds of vegetable oil, including standard motor oil which comes from castor beans.


If you've up a road and completely out of a oil and running from zombies, you can actually use vegetable oil...if absolutely necessary...if you change it immediately...

You should choose a high temperature tolerant oil, so avoid olive oil. Canola or coconut would work better.


Coconut oil probably would not be a good choice at all unless you were in a very warm location. Coconut oil solidifies at 76° F.


I can tell olive oil works fine in 2t 125 scooter. It was one time thing under very special conditions. Nothing bad happens except my clothes smells like French fries.

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