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My mechanic has recommended that I fix an oil leak in my car.

My car is old and really, I rarely drive it so I'm reluctant to spend any money on fixing it unless it's going to cost more later on or if it's going to be dangerous.

With the oil leak, the mechanic says that the oil leak is leaking out the engine and onto the exhaust and could potentially start a fire.

Just wondering, is this a real possibility or is the mechanic just being a little alarmist to try to get me to pay a little bit more?

If it is a possibility, is it one of those things where I'll be driving down the road and all of a sudden, my bonnet will be on fire or is it more likely to smoke first and i would have time to get out of the car first etc.

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  • How big is the leak, when does it leak, and where does it leak from? These are all questions that must be answered to confirm or deny that it is a fire hazard. An oil pan leak won't, a valve cover gasket pouring out oil onto the exhaust manifold very well could.
    – Lathejockey81
    Commented Mar 28, 2015 at 1:54

6 Answers 6

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It is entirely possible. Here is one of many videos on YouTube.

car on fire

Unfortunately, it is impossible to predict how much time or warning you will have before a car fire can occur. If you don't have the money to fix it now you should at least make certain that oil isn't allowed to drip directly onto the exhaust. I know the video may seem like the extreme possibility but, that is what you should keep in mind when dealing with flammable fluids and materials.

EDIT

Adam Wallace at voices.yahoo.com...

If oil leaks on your exhaust, it can be dangerous. The buildup of oil on your exhaust can potentially cause a fire. A car fire is something that nobody wants.

Charles C. Roberts, Jr., Ph.D., P.E. at croberts.com...

  • Volkswagen

    Burn patterns indicate that the cap was not on the oil filler neck at the time of the fire. Crankcase pressure expelled oil out of the filler neck onto hot exhaust components, causing the fire.

  • Unnamed Vehichle

    ...caught fire shortly after leaving a service station, after an oil change. Engine oil had been blown out of the oil filler neck onto hot engine components, causing the fire.

  • Pick-up Truck and Transmission Oil

    ...A fire developed under the transmission boot area while the vehicle was towing a heavy load, which was within the capability of the vehicle. Figure 5 is a view under the vehicle with an arrow pointing to a transmission oil cooler tube fitting that apparently leaked transmission fluid, which then sprayed all over the undercarriage of the vehicle. The transmission oil sprayed onto the exhaust pipe, causing a fire in the vicinity of the transmission oil leak.

Evelrod at eng-tips.com...

If the leak is big enough it can burn that sucker to the ground! (Been there , done that. 350 Chevy C-250, summer ,1981)

Debbie Murphy/autoMedia.com on mobiloil.com...

...check for oil leaks and always use a funnel when adding oil. Oil spilled on a hot exhaust manifold can cause a fire.

If you have a gas station attendant add oil, double check that the cap is on securely. This sounds obvious, but better to check than end up with oil all over your engine compartment at best, or an engine fire at worst.

Burning car

Another video on youtube.com

video of car fire

The flash point of Mobile 1 10w30 motor oil is 232 Deg. C. according to its data sheet.

Exhaust gas temperatures can range widely depending on the car. An average I've found mentioned is 149 Deg. C. at idle to 760 Deg. C. at high load and rare extremes of 1200 Deg. C. Below is a quote by "the solitaire"from sportscarforums.com

EGT (exhaust gas temperature) can easily range between 300 degrees F at idle and 1400 degrees F at high load.

The 232 Deg. flash point of motor oil easily falls within the range of exhaust gas temperature.

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  • A bunch of pictures without context and other people's opinions don't really qualify as evidence. I'm open to hearing another side to this issue, but I think it should be supported by documented facts and reasoning, rather than sensationalism.
    – R.. GitHub STOP HELPING ICE
    Commented Sep 10, 2013 at 5:25
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    @R.. Charles C. Roberts, Jr., Ph.D., P.E. is hardly interested in sensationalism. He's a professional in accident reconstruction and investigation. Admittedly, I did make some references to people with original claims but, I also peppered my post with plenty of respected sources. I wasn't completely finished editing when you made your comment. I've also added a data sheet on 10w30. Wikipedia says "reducing its tendency to burn". It does not say that it does not or will not ignite, only that a low flash point is desirable. The pictures are links to the context except for the quoted image.
    – Seminecis
    Commented Sep 10, 2013 at 5:43
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    @MarkJohnson I agree. Even if a single drip ignites it won't sustain a fire. Realistically it is the buildup of a slow drip over time that could cause issues. I've read buildup being cited as cause of fires but, I'm not sure how quickly oil builds up. I think the two situations to avoid would be a fast leak onto the exhaust and a slow leak onto the exhaust on a car that sits long enough for buildup to occur. I think a slow drip onto the exhaust on a car that is driven daily would burn away without causing a fire.
    – Seminecis
    Commented Sep 11, 2013 at 8:54
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Indeed, an oil leak in a hot area is a car fire waiting to happen. Example: https://en.wikipedia.org/wiki/Pontiac_Fiero#Engine_fire_reputation

"...oil to escape and come into contact with engine parts. The oil would catch fire when it contacted the exhaust manifold or hot exhaust components..."

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Engine oil starts to evaporate at around 400F (200C). The fumes are then flammable so if the oil is built up on some hot parts of the vehicle it could be dangerous.

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Yes.

I have had personal experience with a car and oil on fire.

My previous car was a leaky Camry/ES300. I did not have the funds to fix any of the leaks at the time and had to continue driving it for work.

At one point, I came off of a freeway and into a low-speed residential/commercial zone and came to a stop before making a right turn. Another car was passing me coming from the opposite side and all of a sudden started honking and honking. I got annoyed and stared at them and they yelled, "your car is on fire!". It was only for a moment, and then the fire was gone, but they described to me where they had seen it:
It was under the car, under around where the oil was leaking out. The fire seemed to have started as I was coming to a stop and then when I started moving again, it went out. The exhaust components were right above this area, and I have no doubt that that is what caused the oil to reach its fire point temperature (@ fire point, fuel sustains ignition for at least 5 sec). "Minor" fire, but very dangerous still. I would guess that there were probably lots of times when it reached flash point and wasn't noticeable (which is even more dangerous for when it finally does catch on fire).

Most likely, the recent freeway speeds caused my engine to be running hotter (coupled with zero air flow for cooling) and coming to a stop most likely caused slightly more of the oil to leak during that instant and whatever oil leaked onto whatever hot exhaust components caught fire, spilled down, and burned completely out before causing any serious problems.

After this incident, I tried my best to find another cheap car that is slightly less dangerous to drive around and was very successful.

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My last vehicle I ended up with a leak on the manifold and I blew the motor and it caught fire so yes it is possible

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Yes, Oil spill is one of the main reasons for car's fire, I have seen a lot of burned cars because of engine oil leakage, so, I do strongly advise you to either stop using your car, or , to rectify this oil leak immediately. Mechanical Engineer

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