Picture this: you’re driving on a highway, and suddenly see something you’ve failed
to notice earlier: your gas tank is almost empty!
You drive to the closest gas station, only to find they have no other gas but 87.
Should you pump it inside your car or not?
What’s the difference between those numbers?
Let’s find out!
First of all, gasoline can actually be different, and it’s not one type fits all.
In the US, the most typical numbers you’ll see are 87, 89, and 92.
In other parts of the world, the numbers can vary, but most common ones are 91, 95, and
98.
The higher the number value, the higher the cost of the fuel, so it might seem natural
to choose the cheapest one and go with it, but it’s not as simple as it sounds.
In fact, these numbers indicate the fuel’s octane rating.
It’s the measure of how well the gas resists “knocking” at the time of combustion — I’ll
get back to this a little bit later.
First, I should explain how higher or lower-octane fuel works with different engines.
It’s a surprising thing to say, but if you have an older car, you’re lucky.
That’s because you generally don’t have to care about which type of gas to pump inside
your vehicle.
Higher octane rating tells you how well the gas would perform with your engine, but in
reality, if your car’s user manual says you can use any fuel, including the 87, the
practical difference will be minuscule.
That means very small.
Yeah, I know you already knew that.
Under normal conditions, 87 and 92 are basically the same.
By pumping the 92, you can slightly reduce your carbon emissions and may notice that
your car consumes a little bit less fuel, but that’s about it.
It all changes, however, when your car’s manufacturer expressly states that your vehicle
should only drive on 89 or 92.
You see, the 87 is a basic type of gas that fits most older cars.
89 is a midgrade octane rating that’s suitable for newer vehicles; and 92 is the premium
gasoline that’s mostly required to drive elite and sports cars, but sometimes even
new middle-segment automobiles can demand the 92 and nothing below that.
Like I said earlier, if the user’s manual states you can use any of the three, then
the choice is absolutely yours.
You and your car will feel no difference whatsoever.
But if the octane rating is important for your vehicle, then you should take note of
that and not use any fuel that has a lower rating than required.
And here’s where we get to the issue I promised to explain a while back — the “knocking.”
The term itself was coined thanks to the sound a car makes when its tank is filled with the
fuel with a lower-than-necessary octane rating.
It gives off an audible “knock” or “ping,” and can even not start from the first attempt.
That’s because the fuel mixes with air in the engine, and if the octane number is too
low, this mixture can combust too early and damage the engine.
Have you ever heard this sound while starting your car?
Let me know down in the comments — now you’ve learned the reason behind it!
Anyway, manufacturers may require a higher octane fuel because their engines receive
more air thanks to supercharging or turbocharging.
The reason can also be in a higher compression ratio, which increases pressure in the cylinders.
The engine becomes more efficient with these features, but a higher octane rating is necessary
for them to work correctly.
More air in the engine means faster ignition, and that can lead to early detonating of the
mix.
With high-octane fuel, this is usually out of the question, which can’t be said about
the low-octane type.
So if you pump the 87 into a car with a supercharged engine that requires at least 89, you’ll
most likely hear that dreaded “knocking” sound as soon as you turn the ignition key.
The damage caused by wrong fuel is not immediate, though.
You’ll probably be able to drive for weeks before encountering any trouble.
On top of that, most modern cars have a protection system that softens the “knocking” effect
and doesn’t let the vehicle take too much damage from the lower-octane fuel.
So answering the very first question of this video, yes, if you’re stuck on a highway
with no other fuel than the 87, you can safely pump it into your tank.
But I’d still not recommend abusing this practice.
In the long run, the cost of repairing the engine will outweigh the fuel economy by far.
In addition, the higher the octane rating, the “cleaner” the gas, so it will both
help keep your car in a good condition and reduce your emissions.
Now if I could just reduce my emissions..
So now you may ask why higher octane fuel costs more, especially since it makes no difference
in cars that can run on the 87.
The reason, though, is quite banal: money, as always.
Higher octane rating is achieved by adding components that boost it, and those are expensive.
The more they add, the higher the cost (which is pure logic).
So buying an expensive car is just the first step in a long road paved with service and
maintenance bills.
Some time ago, however, a new type of gas appeared on the market, and it has a separate
label: E10 or E15.
The letter E stands for ethanol, while the number indicates its percentage in the fuel
— 10 or 15%, respectively.
Most gas sold in the US contains up to 10% of ethanol, and car manufacturers approve
of its use in their vehicles.
With E15, the situation is a little bit more complicated, but still many automakers design
their cars to fit this type as well.
And finally, there’s also E85, or flex fuel.
This type contains anywhere from 51 to 83% of ethanol, and only several car manufacturers
allow its use in their vehicles.
Ethanol is basically one of the most efficient additives in gasoline.
It has a high octane rating by itself (about 109), it’s much safer for the environment,
it’s renewable, and it reduces dependence on oil.
Ethanol is made from plants, such as sugar cane or corn, and the easiness of its production
helps keep its cost pretty low.
So why don’t we just switch to ethanol-based cars then?
Well, if only it could be that simple.
First of all, ethanol is one-third less efficient than pure gasoline.
It means that if you can drive for 3 hours on 100% gasoline, you’ll only have enough
100% ethanol for 2 hours’ ride.
Now make it days, and you’ll see how drastic the difference is.
Secondly, only the newest cars allow for E85 to be used, so it’ll take a lot of time
for all manufacturers to adopt this type of fuel.
And thirdly, there are precious few stations that have ethanol-based fuel at their disposal
yet.
And let’s not forget about other types of vehicles, such as electric-powered cars, that
are more efficient in terms of pollution than ethanol-driven ones.
Electric cars just might drive both gas and ethanol from the market and replace them completely.
Alright, we’ve covered the topics of octane rating and ethanol-based fuel, but I can’t
get rid of the feeling that we forgot something…
Ah, yes!
The diesel engines!
What’s wrong with these guys?
Nothing, in fact.
They’re just absolutely different from gas engines in the way they work.
So what could happen if you accidentally (or on purpose, although I’ve no idea why you’d
do that) pump diesel into your gas-powered car?
At first, you’ll drive as if nothing’s wrong.
That’s because the engine will use up the remains of gasoline in the tank.
But as soon as those last few drops are expended, your car will just stop.
It happens because diesel and gas have different ways of combustion, and what works for gas
is useless with diesel, and vice versa.
You won’t be able drive any further with diesel in your gas tank, so you’ll need
to tow your car to the service station cand drain it.
Don’t worry, though: since the engine doesn’t work, no damage is usually done to the internals
of your car.
But if draining doesn’t help, you should prepare yourself to shell out a hefty sum
for disassembling the engine and putting it back together again, dry.
If the opposite happens, however, and you fill your diesel tank with gasoline, things
get much worse.
You see, diesel isn’t just fuel; it’s also a lubricant — a quality which gasoline
lacks.
And if gas-powered engines can’t combust diesel fuel, diesel ones are actually able
to fire up gas.
But it doesn’t really help the situation.
Gas will detonate too early upon combustion, creating that same “knocking” I told you
about before and damaging the car from inside.
It will also leave the fuel-injector pump without lubrication, which can lead to its
rapid failure.
All in all, if you make such a mistake, be prepared to replace some parts of your car.
So remember: when choosing fuel for your vehicle, and you’re given a choice of several grades,
you can proudly decide at the pump, and say: Diesel work just fine, fill ‘er up!
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