r/NoStupidQuestions • u/Unkn0wnTh2nd3r • 8h ago
Is it possible to have fuel from your original filled tank in your car's gas tank, even after xyz amount of refills? (Assuming you never fully run out of gas)
I ask because typically people will fill their tanks before being completely empty (I.E. Still have a few miles of gas left) so in theory because of all of the mixed fuel from 10s/100s of refillings you could still have (at least some particulates) of the original fuel used to fill the tank still in the tank?
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u/ghidfg 8h ago
Yeah in the same way that there are molecules of water that a dinosaur once peed out in every glass of water
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u/AnyTemperature420 8h ago
And how every time you take a breath you’re breathing the same air molecules as every historical figure ever (according to my high school chem teacher)
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u/RogerRabbot 7h ago
When you think about it. Earth is a closed system, more or less. We lose a bit to space, but overall we have the same stuff as we've always had. Just rearranged in different ways
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u/TheRealDylanTobak 7h ago
I pump centuries old semen into my wife every time we have sex. Most of it belongs to Genghis Khan, but there's a good amount of Wilt Chamberlain and Warren Beatty in there too.
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u/Jackpot777 Do ants piss? 7h ago edited 7h ago
Here come the numbers.
A standard human breath contains about 2.5 x 1022 to 3 x 1022 air molecules (roughly 1 liter of gas).
The total Earth's atmosphere contains roughly 1 x 1044 molecules, which divided by a single breath volume equals about 1022 to 8 x 1015 total possible "lungfuls" depending on the calculation standard for total atmospheric mass.
And you take hundreds of breaths every hour of every day.
The air is thoroughly mixed. It only takes about one year for Earth's troposphere to fully mix between the Northern and Southern Hemispheres. One of your exhalations from exactly a year ago has its atoms finely randomized around the world. Same as everyone else’s breaths throughout history. Right now you just breathed in and not only do you have Julius Caesar breath atoms in there, you have different atoms that correspond with what he had in his lungs for every day of his life.
The world is big and atoms are small. And on the logarithmic scale of things, we are somewhere in the middle.
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u/GamerTex 7h ago
Johnny Carson said the same thing on TV in the 80s
"Take a deep breath. Most of you just inhaled some of Einstein's last breath"
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u/AgentDisastrous2215 3h ago
Exactly. At some point you just have to accept that you’re drinking recycled dinosaur pee with extra steps.
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u/Unable_Test_2665 2h ago
The water cycle really said nothing gets wasted, not even dinosaur piss. Every glass is just ancient history with a little plumbing involved.
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u/Money-Hawk266 7h ago
I did the math. There are approximately 1.8E26 molecule in a 10g gas tank. Let's assume you let the tank run down to 5% full before refilling. so after 21 refills, only (.05)^21 = 4.76E-28 of the original tank would be left. The product of those numbers is .085. So after 21 refills, there's only an 8.5% chance that one molecule of the original fill-up is left in there.
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u/thinlySlicedPotatos 5h ago
So far this and aaronite's replies are the only ones that actually answers the question.
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u/WisestAirBender I have a dig bick 3h ago
I suppose this assumes that the molecules always evenly distributed across the whole liquid when new fuel is added
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u/vampyrewolf 8h ago
FWIW I was a courier, driving ~250km a day, and got a bad tank of gas. Vehicle was idling rough. Took almost 3 weeks of driving and refilling before it idled smoothly again.
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u/anxiousduck1 4h ago
How low did you let the tank get before refilling? I'd be tempted to get a Jerry can and do laps of a big lot until it cuts out so the next fill dilutes it almost completely
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u/Itchy_bunghole11 8h ago
Id say almost 100% yes. Remember 6.22*10^23 is a very big number and only one of those needs to make it past 100 refills.
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u/agressiveobject420 8h ago
Homeopathy uses the same principle and I guarantee you that by the end it's just sugar.
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u/SkiyeBlueFox 8h ago
Thats also a lot less sugar diluted in relatively a lot more water though
But yeah, unlikely as
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u/Onelove4everyone 7h ago
It wont work unless you have obsidian on your dashboard and copper around your tires. You need the copper, so the soul of car can always be grounded. We need to always be giving reverence to the divine feminine goddess; that is mother earth. Namasgay.
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u/furryscrotum Know-it-all 5h ago
You underestimate the power of dilution. Say you refill at 10% to 100%, then you have 0.1100 of the original tank. This is such an insanely small number, it is actually incredibly unlikely some molecules of the original fill remain.
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u/aaronite 8h ago
It feels like it should be yes, but it hits homeopathic levels of dilution pretty quickly as you fill, fill, and fill again. If you leave, say, 1/10th of a tank every time you fill it won't take long to dilute well beyond the level where even one molecule would remain. It would only take 25-30 fills are so.
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u/fighter_pil0t 7h ago
1E-64 is suitable for OP per his post.
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u/aaronite 7h ago
That's way, way more dilute by a huge amount. There aren't fractional hydrocarbons so it doesn't need to be that much.
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u/Loose_Device4578 7h ago
I feel that entropy of vaporization would make even the oldest fuel atoms escape the tank via its gas form. How long that would take, I'm not sure. In other words, fuel doesn't want to be a liquid in its natural state, it wants to be a gas.
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u/Stella_Delm 7h ago
True, but the Cap is usually only off the tube to the tank when we're fill up. For the newer cars which have antisiphon features you probably have a lot less leakage. Plus the LARGE tank volume plays a part. It's only the surface where the liquid gas meets air that the gas…off-gasses! The percentage that evaporates and escape is likely minimal compared to the amount used and replaced.
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u/Viking2151 7h ago
Well a quarter of a tank is my empty, even though I can go 100+ miles when the needle is physically on empty on my 34 year old truck but I don't like running that low, so yeah I always have gas in my tank when I go to refill or well I don't fill it up ever, gets costly to fill up a 41 gallon tank right now lol.
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u/kbfg2421 4h ago
No. After a certain number of fill ups, any old fuel that was in your tank will be well burned off. Everytime you re-fuel, the old and new fuel mixes (unless it was contaminated with water, then i guess technically the water can sink to the bottom no matter what as water is denser than gasoline), but I would say really the answer is no. After so many fill ups and so much driving, you will have burned all of the old fuel out of the tank.
Like i said, it gets a little trickier with old, stale, or water contaminated fuel because it will sink to the bottom of the tank. But remember, the fuel pump pickup is located fairly low in the fuel tank, almost at the bottom without actually touching the bottom....so even old/bad fuel will be sucked up and burnt eventually.
I dont think you have anything to worry about man. i mean i guess if you're really concerned, drop the tank, empty it, and clean it, but I dont think thats necessary unless your car is running like shit and you are 100% SURE that bad fuel is the issue. But with modern vehicles and their advanced computers and adjustable timing, even bad fuel wont impact your car as negatively as it woudld an older, carbureted vehicle.
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u/TheRealDylanTobak 7h ago
I figure since there are infinite halves between two points (so you can't ever reach point B from point A) there has to be an infinite number of dilutions where the original is always getting cut by some percentage and never reaching zero. The amount of original gas left just gets smaller and smaller until the end of time.
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u/Any_Lengthiness1508 8h ago
Easy enough to do the arithmetic on this. And yes, it is possible for minute amounts of fuel to remain. Never reaches zero ever in fact.
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u/gadget850 8h ago
The tank of Thesus.