56 votes
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Why do heavy vehicles almost always use diesel engines?

Torque is the name of the game. High torque is needed to move heavy loads. If comparing a gasoline engine to a comparable diesel engine the diesel will always have higher torque. The higher torque ...
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  • 15.9k
46 votes
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Do cars consume less gasoline when the tank is full?

No. If anything you'll get worse gas mileage with a full tank because you're carrying a heavier load (more fuel = more weight). What you are most likely experiencing is the top half of the tank is ...
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28 votes

Should I really keep my gas tank at least half full?

I'd suggest there's credence for all of these Your fuel pump overheating if it runs dry Unbeknownst to most, the fuel in the tank cools the fuel pump in most vehicles. The pump sits in a ...
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27 votes

Why do heavy vehicles almost always use diesel engines?

A major, but often overlooked, reason for the dominance of gasoline engines in passenger vehicles is the need for diesel engines in heavy vehicles. A given quantity of crude oil, depending on its ...
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  • 1,713
27 votes

Why do we mostly use fossil fuel instead of a more reliable and larger sum fuel?

What you really want to look into is Energy Density. So called "Fossil Fuels" have a very high energy density, which is very important for a vehicle fuel since you have to load it and carry it around ...
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  • 13.2k
26 votes

Wrong octane fuel

It's not a problem mixing them. Just start using 95 if that is what the engine calls for. You'll not create any issues doing so. Modern day engines have sensors which can adjust for the fuel. If ...
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23 votes

Why do we mostly use fossil fuel instead of a more reliable and larger sum fuel?

While energy density is a rather nice property of gasoline and diesel, it's not the primary driver of their use. Instead, the primary driver is a rather practical one: they're cheaper. On the ...
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  • 331
22 votes

Why do heavy vehicles almost always use diesel engines?

To OP’s main question: “Why do heavy vehicles almost always use diesel engines?” Answer: Cost and dependability. Diesel engines are significantly more expensive, but have lifetimes many times greater ...
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22 votes

Haven't driven a car since the start of the pandemic; can it be driven without special measures?

Cars are routinely left parked for three to six months or more without running, with no ill effects. I wouldn't hesitate to jump it and see if it'll start. As @BrianKnoblauch comments below, jumping a ...
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21 votes
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Should I use gasoline 87, 89 or 93 on 2016 RAV4 SE

Realistically, if the manual and the manufacturer are stating you should use 87 octane, that's really what you should use. If you purchase more expensive 89, 91, or 93, you are just wasting money. The ...
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17 votes

Why not use gasoline on diesel engines or vice versa?

You "can" use diesel in a gasoline engine. In the sense that it will run, but it will run poorly and smoke A LOT. But the problem with gasoline in a diesel engine is that diesel engines rely on ...
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16 votes
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Why does diesel engine have redline much lower than petrol engine redline?

In Short its based on low burn rate of diesel plus the longer stroke of the diesel engine. First you must understand the difference between these engines, the diesel works on purely compression of ...
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14 votes

2020 explorer will not fill up

Are you sure the gas station was open? I recently had the same problem and found that the lights were fully on at the station, the digital readouts on the pumps were glowing, but the place was ...
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  • 1,544
14 votes

Do cars consume less gasoline when the tank is full?

The best way to determine the actual fuel consumption is to brim the tank, drive till nearly empty then brim the tank again. Then you have an exact volume of fuel and a specific distance. Repeat over ...
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13 votes

Why not use gasoline on diesel engines or vice versa?

I would say there are two major reasons. First, the seals and o-rings used in diesel engines can't tolerate the chemical composition of gasoline. They are designed to tolerate the chemical ...
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  • 15.9k
12 votes
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Why is there a hissing noise when I open my petrol cap?

Regulations limit the amount of unburnt hydrocarbons that can be released into the atmosphere, therefore fuel tanks on cars now have to be sealed to stop these emissions. The noise you hear is air ...
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  • 20.8k
12 votes

Do cars consume less gasoline when the tank is full?

IF - the tank was uniform in its dimensions - vertical sides, etc., and IF - the gauge sender worked exactly in a linear manner, and IF - the gauge responded in that same linear manner, and IF - the ...
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  • 428
11 votes

Why do heavy vehicles almost always use diesel engines?

Given two engines of similar weight, both operated at their respective optimum efficiency (i.e. maximum mechanical work done per unit of chemical enthalpy in the burnt fuel), you will end up with ...
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  • 111
11 votes

Wrong octane fuel

Presumably since you say "92 octane gas" you are not in Europe. The whole topic is a mess, because there are different scales for measuring "octane". The most common scale world-wide is RON, but ...
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  • 2,929
10 votes

Why does a petrol engine need to maintain an air-fuel ratio, while a diesel engine doesn't?

It sounds like you already know why a gasoline engine keeps the fuel/air ratio as close to the stoichiometric ratio as possible, but just for the sake of information for anyone else: The ...
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  • 2,045
10 votes
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Does the mileage indicate the quality of the gas?

It is not likely the quality of the gasoline causing the change. The sensors are unable to evaluate the chemical makeup of the fuel. It could be a change in your driving habits, changes in temperature,...
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  • 9,035
9 votes

Old gas in 2 cycle engine

Gasoline sitting for two years in the float bowl of a carburetor will surely lead to some varnish. The hydrocarbons evaporate from the fuel and oxygen acts as an oxidation catalyst changing the ...
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  • 32.8k
9 votes
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Why not use gasoline on diesel engines or vice versa?

You can run gasoline in a diesel motor, but it causes problems. As mentioned elsewhere, when you compress the fuel/air mixture enough, it gets really hot then ignites. With diesel, this is ok, because ...
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  • 617
9 votes

Why not use gasoline on diesel engines or vice versa?

You can see the ill-effects of misfueling in this episode by Fifth Gear. They put petrol (gasoline) in a diesel car and vice versa. A summary of the differences between the two fuels: Diesel does ...
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9 votes
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Is it necessary to turn off the engine while refuelling?

Here is a link from the API (American Petroleum Institute) website. http://www.api.org/oil-and-natural-gas/consumer-information/consumer-resources/staying-safe-pump The article is called Staying safe ...
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  • 3,842
8 votes

What causes more gas consumption - Idling with AC or Heat?

Definitely air conditioning requires more energy, since heat is, as correctly stated in the other answer "basically free" because it's the waste heat from your engine. According to this study by R. ...
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  • 2,827
8 votes

Why does "i" stand for petrol?

It stands for Injection as in Fuel Injection.
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  • 2,750
8 votes
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Why does "i" stand for petrol?

The i is a leftover from the 1970s, when a few companies (BMW and Mercedes, notably) started replacing the carburetor on their petrol engines with fuel injection. The marketing department saw an ...
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  • 4,412
8 votes

Haven't driven a car since the start of the pandemic; can it be driven without special measures?

If you have the ability and access to some tools, remove the battery and bring it to your local national auto parts chain ie: AutoZone, AdvanceAuto Parts, Oreillys etc. You may want to call first to ...
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  • 19.7k
7 votes

How can I determine if it is more cost effective to run premium fuel in my car?

The simple fact is, it's all just mathematics. For instance: (Note: I'm just throwing numbers out here, it's the mathematics which are important.) Given: 20 gallon fuel tank If you are using 93 ...
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