What's the difference between the different grades of gas you use in your car?

Question

I use 89 octane I can't afford 93 will it damaged your vechicle to use the lowest grade?

Answer 1

The difference is in the antiknock capabilities of the gas. The higher the octane the more compression it can stand without detonating. That is where you get the ping in the engine.

Use the type of gas that the manufactures recommends. Using a lower grade of gas will make your car perform at a level below what it is supposed to.

Good luck.

Answer 2

It depends on your car whether it will cause damage.

The different grades of gas have different "octane ratings." This supposedly has something to do with the amount of octane as opposed to other hydrocarbons in the gas, but can really have more to do with the gas composition being such that it will behave like it has a certain amount of octane.

What a higher octane rating means is that the gas will be more resistant to ignition. It is harder to start it burning. This is useful in engines with high compression...engines that deliver a lot of power from each combustion stroke. Engines like you'll find in sports cars. Anyhow, high compression creates a lot of heat during the compression stroke. That heat can cause lower-octane fuel to "preignite," Or explode from the pressure of the compression stroke rather than from the spark at the beginning of the combustion stroke. Diesel engines operate on this principle, but gasoline engines are not designed for it, so preignition can cause damage.

You will usually know if you're getting preignition because you'll usually hear a knocking or pinging sound, and you may have a noticable loss of power. A lot of things can cause this, but chief among them would be overheating (coolant leak or head gasket failure are common causes), and, from what I've been told, bad piston seals.

Neither of these are cheap to fix, even in a cheap car. (well...the coolant leak can be) But if you have a car that usually runs low-octane, and it's knocking, you can often keep driving by running high-octane fuel.


Anyhow, back to whether you should use it: Many modern cars can be run on pretty much any pump gas, the engine computer will adjust things to match the fuel that's being used. Most older cars, however, do not. Running high-octane fuel in a vehicle that calls for low-octane will almost never hurt it. Running low-octane fuel in a car designed for high-octane "premium" gas (usually just sports cars, and other performance cars), however, can cause damage.

Read your owner's manual, and assuming you don't have some problem which calls for you to use premium, just run whatever the manual recommends.

If your car is just fine, and calls for low-octane gas, premium IS NOT worth it.

Answer 3

Unless your car specifically requires premium gas (like in certain luxury cars) then "plus" or "supreme" unleaded is just a waste of money. Cars today are designed to run on 87 octane, and in many cases higher levels of octane can damage your catalytic converter leading to decreased mileage. As far as the differences between companies, think Dasani water vs. Ozarka water. Subtle differences, but they're both wet, you you can drink em both.

Answer 4

use what the manufacturer recommended for your car ( call a car dealership if you dont' know ). Unless you have a high-performance car, you don't need 93, and most likely not 89. Most all small, modern cars with 4-cylinders usually run on 87 just fine. if you start getting knocking under hard acceleration, then you need to move up a grade. That's the easiest way to tell. Run on 87, try to accelerate hard. If it goes with no noise, you're ok.

Answer 5

E85 is flex fuel. 87 and 89 octane is not much difference between them. 93 octane is for motor cycles and classic cars. It will not damage your vehicle running lower grades.