In the third movie Marty finds the Delorean in the mine and travels from 1955 back to 1885 to rescue Doc Brown. However once they establish that petrol hasn't been invented and won't be for a long time yet, why doesn't it occur to them to simply go to the mine where Doc left the car and empty the tank from the Delorean to the car Marty brought back in time. They would both exist. I know it would then ruin the film but isn't it obvious and wouldn't Doc think of this seeing as its only been relatively months since he put the car in the mine?

  • 1
    It's the same car. I believe it's called a "Bootstrap Paradox" or an ontological paradox. Once the Delorean travels back from 1955 to 1885 it no longer exists in the mine. – Monty129 Feb 21 '14 at 21:45
  • 6
    That isn't true in BttF. At the end of the first movie Marty watches himself go back in time, in the same DeLorean he had just gotten out of a few minutes before. So for that small time there existed two of the same DeLorean in 1985. – Xantec Feb 21 '14 at 21:48
  • 7
    There's nothing inherently paradoxical about two differently-aged versions of of the same object existing in the same time period. The bootstrap paradox refers to an object whose history forms a closed loop with no origin, like the one with the watch in "Somewhere in Time" discussed here: friesian.com/paradox.htm – Hypnosifl Feb 21 '14 at 22:08
  • I seem to have misinterpreted the looping nature of the paradox then, my apologies. – Monty129 Feb 21 '14 at 22:20
  • 1
    For the record, a high-performance engine won't run well (or at all) on fuel that's been allowed to oxidise for more than 6-12 months. – Valorum Feb 22 '14 at 17:01

Per hypnosifl's comment, Robert Zemeckis covered this specific point in a Q+A session in 1993 for the "Hill Valley Telegraph Issue #8"

"Interviewer: In 1885, when Marty tells Doc they're out of gas; why don't they just go to the Delgado Mine, dig up the DeLorean where Doc hid it and get the gas out of it?

Zemeckis Answer : "There are two logical answers to this one…

The car mechanic's answer: As anyone who has stored an automobile for a long period of time can tell you, you always drain all of the fluids out of the car before putting it into storage. Doc most certainly would have drained the gas out of the DeLorean if he was going to leave it hidden for 70 years. At the 1955 drive-in, Doc specifically says "I put gas in the tank" indicating that the DMC must have had an empty tank when they found it in the mine.

The time travel theory answer: Even if Doc had not drained the tank, he still would not have gone back into the mine for fear of creating a time paradox by accidentally damaging the DeLorean, the mine, or who knows what. After all, since Marty is now back in 1885, Doc's plan obviously worked, and worked perfectly. But what if Doc were to go back into the mine and accidentally cause a cave-in that causes even more damage to the DeLorean? What happens to the future of that DeLorean, when it's unearthed in 1955? And what might that do to Marty and the undamaged future DeLorean now in 1885? As an analogy, imagine a time traveler going back in time, finding himself as a child, and cutting off that child's hand with a meat cleaver. What happens to the adult time-traveler's hand? That would definitely risk a time paradox, and we know that Doc would never go out of his way to risk such a thing for fear of (in the worst case scenario) unraveling the fabric of the space-time continuum and destroying the entire universe.*

  • 9
    however the damage may be limited just to our own galaxy – JoelFan Dec 19 '14 at 3:14
  • 8
    Doc: I foresee two possibilities. One: coming face to face with herself thirty years older would put her into shock and she'd simply pass out. Or two: the encounter could create a time paradox, the result of which could cause a chain reaction that would unravel the very fabric of the space-time continuum and destroy the entire universe! Granted, that's a worst-case scenario. The destruction might in fact be very localized, limited to merely our own galaxy. Marty: Well, that's a relief. – JoelFan Dec 23 '14 at 17:12
  • 1
    Then again, where did Doc Brown empty the tanks to, knowing he might need the petrol again? – Zommuter Jul 16 '15 at 10:21
  • 1
    Good point. Though the Doc might have come up with one of the stabilizers mentioned e.g. here, he did build an Espresso machine after all... – Zommuter Jul 16 '15 at 11:37
  • 1
    @Zommuter why bother with inventing a stabilizer when gas is readily available in 1955? – Anthony X Oct 28 '18 at 19:34

At the point that Marty went back to rescue Doc in 1885, the Delorean had already been sealed up in the mine. As part of putting a vehicle in storage for 70 years, Doc would no-doubt have drained all fluids including gasoline since those would degrade and gum up sitting for that long. We are shown that Doc had some fore-sight into the effects of storage, as he put the vehicle up on blocks to account for the tires rotting away in that time, so we can assume he was familiar with other aspects of long-term storage of vehicles.

While not shown on screen, Doc and Marty certainly had to give the engine fresh oil and gas as part of getting it ready to travel again after digging it out in 1955.

  • 4
    And while Doc most likely saved the fluids, IIRC it had been a few months since Doc arrived in 1885, so he likely already used whatever gasoline there was. – Xantec Feb 21 '14 at 21:46
  • So what he just chucked the petrol he drained from the car? If he had great foresight he wouldn't have let Marty go back from 1955 to 1885 without plenty of petrol and would not have disposed of a valuable substance when he was in 1885. – Pompom78 Feb 21 '14 at 21:47
  • 2
    @Pompom78 No, I doubt he chucked it. But he likely used it in setting up his blacksmith business. As for not sending Marty back with plenty of fuel, they probably filled the tank before he left, but that all would have been lost when the fuel line broke. And since they weren't planning on a long road trip on 1885, why bring a fuel can? – Xantec Feb 21 '14 at 21:50
  • 3
    I don't think either 1955 Doc nor Marty thought it would be anything more than a quick trip to pick up 1885 Doc and return. Neither counted on ripping a hole in the fuel line. – Monty129 Feb 21 '14 at 21:51
  • 1
    The notion that Doc drained the tank is also the answer given in the official BTTF FAQ, where answers to common questions were provided by Bob Gale and Robert Zemeckis (they also mention a second issue where Doc would be afraid to dig up the DeLorean for fear of accidentally damaging it and creating a paradox): bttf.wikidot.com/official-bttf-faq#toc19 – Hypnosifl Feb 21 '14 at 22:05

Since the BTTF movies have many repeated consistencies like skateboard chases, bad clothes (life preservers and moccasins) and Doc being habitually forgetful (who dressed Marty in that Clint Eastwood outfit) ... then it is possible that the same Delorian had a gas leak on both occasions when entering 1885 (and possibly both caused by Native Americans and/or lightning). The 1955 Doc simply forgot to tell Marty that he also fixed the minor gas leak before sending Marty to 1885.

  • The iteration of Doc who got trapped in 1885 had not yet dressed Marty in the horrible 'western' gear. He never had any need to, because he hadn't yet been trapped in 1885. If he had, he'd have also known to pack spare components for the time circuits, and none of the events in the movie ever would have needed to happen. Remember, when time travel is involved, causality can be tricky to lay out. – Theo Brinkman Dec 17 '15 at 18:54
  • @TheoBrinkman : The Doc who got trapped in 1885 HAD in fact dressed Marty in those ridiculous clothes already, because he (the one stuck in the old west) is the Doc from 1985, so he could have remembered about having dressed Marty back in 1955. But it's understandable that he could possibly forget that detail after 30 years had passed since then (plus several time-travelling adventures to the future and the past that led him to being stuck in 1885). – OMA Sep 4 '18 at 16:11
  • All that's assuming that if someone's past changes (even if it's just a small detail), the knowledge of that change naturally passes on to the future versions of the affected people, doesn't it? – OMA Sep 4 '18 at 16:20
  • @OMA, but the Doc who helped Marty go back to 1885 can't have been a Doc who had already been trapped in 1885, otherwise he would have known about everything that was going to happen, from the blown gas line, to the letter. Doc was a bit scattered at times, but isn't that senile. Remember, when you're dealing with time travel, just because you're older doesn't mean you've already experienced everything that has come before. We already know, from the first & movie, that the timeline can be altered permanently by actions taken in the past by a visitor from the future. – Theo Brinkman Sep 4 '18 at 20:53
  • @TheoBrinkman : The Doc who helped Marty go back to 1885 was a younger doc who still hadn't been trapped in 1885, BUT then he went on to live another 30 years (from 1955 to 1985) and it's at that time (1985) when he travelled to the future of 2015 to fix the issue with Marty's son, then went back to 1955 to burn the almanac and finally got the problem with the DeLorean's circuits during the storm that led him to travel back to 1885. It's precisely because timelines can be altered the reason why he could have remembered about having helped Marty 30 years prior to the time he lived on (1985). – OMA Sep 6 '18 at 15:38

Doc used the gasoline, oil, tranny fluid, power steering fluid and radiator coolant to fabricate parts for his refrigerator. Then to run the refrigerator.


I think it is safe to assume that his fuel tank was probably damaged by the fall back to earth when Doc Brown's DeLorean was transported back to 1885 and 40 feet up above the ground with a non-functioning hover conversion ;) ...boom

  • But remember, the DeLorean that Marty drove from 1955 to 1885 at the start of part III was the same one Doc had buried in the mine in 1885--it seemed to run fine until the fuel line got hit with an arrow. – Hypnosifl Feb 25 '16 at 4:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.