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Does It Really Matter What Kind of Gas I Put in My Car?

A diesel pick-up truck.
A car's gas cap.
Diesel vehicles must use diesel fuel.
A man filling up his car with gasoline.
Diesel is available at most filling stations.
Sports cars may need high octane gas.
Most cars are built to run on economy fuel, with more expensive varieties bringing little added benefit in terms of performance.
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  • Written By: Tricia Ellis-Christensen
  • Edited By: O. Wallace
  • Last Modified Date: 16 August 2014
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In general, it does not matter what type of gas one uses in a car. Most cars are built to run on economy gas, and giving them higher octane fuel is rather like giving a treat to an overstuffed dog. It’s not necessary, it provides no additional benefits, and it will cost more.

However, some people believe that what kind of gas is used, rather than octane measurements, seem to make a difference in car performance. This can generally be attributed not to the fuel itself but to types of additives it contains. Thus for some people, there can be a difference between one company’s brand and another company’s brand. For many, this makes no difference either.

Some cars do require higher octane gas. In general, an owner’s manual will inform the owner of this fact. For example, if a car has a high compression engine, as do many luxury or sports cars, they may require an octane rating that is higher. This is the case with cars like Porsches or Jaguars.

Generally, the purpose of higher octane gas is to prevent knocking or pinging in the engine, and to increase performance. Occasionally a very loud knocking can damage the engine. Knocking sounds are caused by the sudden ignition of fuel, which occurs almost instantaneously. The sound reverberates throughout the cylinder causing an audible ping or knock sound.

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If the driver can eliminate knock by using higher octane gas, then it may be worth the extra money to do so. Though minor knock is unlikely to damage a car, consistent and loud knocking can. So occasionally, the owner has to ignore the manufacturer’s instructions and dig deep for the high performance option.

There is a very important distinction between using gas and diesel. Diesel fuel cars will die on gasoline, and the process of cleaning out regular gas in a diesel engine can be highly expensive. If a person own a diesel car, do not use regular gas of any kind. Only use diesel fuel, commonly available at most filling stations.

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anon947359
Post 10

One should realize that the MPG testing done by the government on all vehicles is performed using the lower octane gasoline.

orangey03
Post 8

@wavy58 – That sounds like something I would have done. When you pull up to a pump and you are in a hurry, things can get confusing.

I try to get my gas at the cheapest station in town, but so does everyone else. This means that someone will always be waiting in line behind me, and I feel like I need to hurry.

Last time I was at this station, I became flustered and accidentally got the high octane gas. I didn't have enough cash on hand to pay for it, but luckily, I had my credit card. I really got upset at myself for that pricey mistake, because my car does just fine on the low octane gas, which is so much cheaper.

seag47
Post 7

I work as a personal assistant, and I often have to drive my boss around town in her Jaguar. She told me when I got the job to always purchase the highest quality gas available, regardless of the price. Money is no obstacle for her.

She told me that her brother also has a Jaguar, and when his business started losing money, he tried putting low octane gas in his vehicle. She said it knocked horribly and he nearly ruined the engine.

I am amazed at the amount of money she is willing to spend on gas. I could never afford to own a car like this, much less fill it up with high octane on a regular basis.

Oceana
Post 6

During a time when gas was very affordable, I used to put mid-grade gas in my car. My dad had told me that it was better quality and would make the engine run more smoothly, and since I knew nothing about such things, I followed his advice.

A few years after I started driving, the price of gas tripled. I could no longer afford to buy the mid-grade, so I decided to try the lowest grade. I was afraid it might do some damage to my car, but I had to try.

I noticed absolutely no difference between the two. My car ran just the same as it had before, and I have been getting the low-grade kind ever since.

wavy58
Post 5

I am glad that gas stations had the forethought to prevent unobservant people like me from putting diesel in their cars by accident by designing the pumping stations differently. When I was in college, I absentmindedly lifted the nozzle for diesel and tried to put it in my car.

I tried to insert the nozzle into the hole, but it would not go. It was too big to fit in there. For a moment, I wondered what on earth was wrong, but one glance back at the pump enlightened me to the fact that I had grabbed the diesel by mistake.

You would think that the bright green color would have alerted me to this, but it didn't. I'm just glad it was impossible for me to mess up in this way.

anon152372
Post 3

Can i run 91 octane in my 2001 nissan primera wagon the engine type is a sr20. i have been told that i can run 91 it will be fine but then i got told no i cannot i need to be running 95 octane. please help me.

anon87199
Post 2

gasoline engines take gasoline. diesel engines take diesel.

anon36449
Post 1

is it okay to put diesel into my buick lesabre 92 or does it apply to the gas in a diesel engine

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