In Back to the Future Part 3 Marty follows Doc back to 1885 to rescue him from being shot at the hands of Buford 'Mad Dog' Tannen. He arrives in 1885 some time after Doc has written the letter that Marty receives in 1955. Unfortunately for them the DeLorean springs a leak and loses fuel, which leaves them short of a way to get the DeLorean up to 88mph. The Mr Fusion only powers the time circuits, but the engine runs on standard gasoline and always has.

Why don't they just use the other DeLorean?

There are now TWO DeLoreans in 1885. The one Marty arrived in and the one Doc has hidden in a mine with repair instructions for his 1955 counterpart. Why don't they just syphon the fuel from that DeLorean?

This may be a plot hole, but there may be perfectly logical explanation for it.

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    Maybe Doc used up the gasoline for one of his experiments. After all, the 1955 versions of him could easily refuel the DeLorean, so why let perfectly good gasoline rot for 70 years?
    – Oliver_C
    Commented Oct 23, 2012 at 21:05
  • There were gas stations around in 1955 so the Doc woulda filled it up so i think it's a plot hole personally.
    – user6511
    Commented Oct 23, 2013 at 20:20
  • The patent for the process to make what people now know as gasoline was filed in 1913. The forerunner of gasoline was around in the 1800s before the invention of the internal combustion engine, but it was only known as a useless by-product of the process used to make kerosene for oil lamps. reference.com/science/gasoline-invented-69694954026c74a1
    – Magno C
    Commented Aug 11, 2016 at 17:43
  • 1
    I think it's a rule of time-travelling: do not tamper with the past. If the other DeLorean had been used, they could be in another alternate future, which they surely didn't want to be in.
    – EKons
    Commented Sep 17, 2016 at 15:35
  • The real question is: Why didn't Doc go to the post office after Marty's arrival and revise his letter to 1955, adding a note: "Bring an additional fuel canister"?
    – Jan
    Commented Nov 23, 2017 at 12:56

8 Answers 8


You do have a point in that the fuel could have been syphoned. However, it's more likely that there just wasn't any. When the doc gets back to 1885 with broken time circuits, he first tries to fix it. When he realizes it can't be fixed, he buries the car in the mine after first draining it of all fluids.

While it is unclear if the car could be dug up, it wouldn't have had any fuel. The doc would have had to keep all fluids that he drained from the car. You could argue that some gasoline could always come in handy, but as the doc mentions in his letter, he is concerned about the space time continuum. Keeping it around in his shop would be dangerous (what if someone found it?) and he wasn't going to use it in a car as he specifically forbids Marty to rescue him. To avoid disrupting space-time, the simplest thing would have been to dispose of all fuel.

The official explanation can be found here. Apparently the time paradox for going back into the mine was too dangerous too go back in. However, Doc could have still drained it and kept it in his shop. Either he didn't want to keep it around (for the danger of discovery) or he didn't see the point in keeping it.

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    Draining the car of all fluids before storage for decades seems to be very likely explanation. That answers my point sufficiently, thanks.
    – Cage
    Commented Oct 23, 2012 at 21:13
  • 1
    Also the car was future-fitted it may not have been running on gas or had any in it for awhile. Commented Oct 24, 2012 at 13:54
  • 4
    Keeping it around in his shop would be dangerous (what if someone found it)... oh, Doc could easily have hidden a canister of gasoline behind the MASSIVE refrigerator ;)
    – Oliver_C
    Commented Oct 24, 2012 at 15:18
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    @KevinHowell the car always ran on gasoline
    – Origin
    Commented Oct 24, 2012 at 15:52
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    Gasoline oxidises after a couple of months, no matter how its stored. He may have siphoned it off, only for it to 'go bad' before finding a use for it. Commented Oct 19, 2015 at 11:23

If Marty & Doc would have dug up the 1885 Delorean, then it wouldn't have been in the cave in 1955. Therefore the Marty in 1885 would possibly cease to exist.

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    Keep the car. Take only the gas. Dããã.
    – Magno C
    Commented Aug 11, 2016 at 17:38

As noted by Doc's letter to Marty, Doc has been in 1885 for 8 months. This is crucial to figure out why the gas, how ever much is left, would not be useful. Gas tends to have a shelf life of 3 months. 8 months is more than twice that. And that's only in ideal conditions. Since Doc likely knew enough to prep the damaged DeLorean for long term storage, which involves in draining all fluids, and that 1955 Doc specifically told Marty at the drive in that he filled it with gas, we can assume it had no 70 year old gas inside. Doc, had he kept it, would have needed a container, and 1885 would not have any quality, gas grade containers (air tight, opaque, low permability).

Gas will go stale within months. And that's modern day Gas, who knows what 1955 gas shelf life is like. The more space in a tank, the more space it has to evaporate. Condensation will add water to the fuel ruining it. Temperature swings will as well. As we know, 1885 had no temperature control to speak of. The older the gas, the less likely it will ignite. Diesel would last longer as it does not need a spark to ignite, just compression.

In short, even if Doc had saved the gas, eight months and imperfect storage would have made it useless by the time Marty showed up.


It's simple. If they would dig up the first time machine it had been siting in the mine for 6 months, when doc got there in 1885. when Marty got there in 1885, the replacement parts to fix it for 1955 would not be available until 1985

  • 1
    Can you be a little more specific? Maybe cite a source, or scene? I suggest checking out the Tour to get a better idea of how to ask and answer questions. We're not a typical discussion forum. Don't be discouraged, we were all new here at some point. Commented Aug 31, 2015 at 21:01

Major plot hole they didn't even need the gas they now had a working time circuit that they could place on the DeLorean that doc arrived


They blew up the engine when they first tried to get it running on whiskey, therefor not having enough time to repair the engine before doc's murder and if they had switched engine parts ir still would have changed space time continuum because the engine parts would not have been availble until the early 80's for the delorean


When Marty went back to 1885 Doc had already prepared the Delorean for a 70 year hybrination. This would have involved draining the fluids, especially gasoline. What good would gasoline be to Doc in 1885 when nothing runs on gasoline? I doubt he would have kept it. The 1885 Delorean was never shown because if it was disturbed or moved, it would not be available for Marty in 1955. As soon as it was moved or changed in any way, Marty and the 1955 Delorean would fade from 1885 existence. The only way the 1885 Delorean would be helpful is if Marty got there before Doc drained the fluids. Then they could have filled the 1955 car with gas from the 1885 car, then prepared the car for hibernation exactly as Doc had done originally. It would be a paradox if even the slightest thing was done differently to the 1885 Delorean so it would have been best to stay away from it completely.


Because if he used the gas in the car in 1885 they wont be able to use the car in 1955 cause theres no gas because they used it in the past there for doc is dead

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    There is gas in 1955, and i don't think a tank of gas lasts 70 years. Commented Apr 21, 2014 at 18:35

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