How to know what octane number my car has

Some drivers wonder if premium gas will make their car run better or regular gas will damage your engine? What about mid grade gasoline and can it allow you better fuel performance? gasoline? Drivers often get the wrong answers to these questions. Here we tell you how to solve in these cases.

See also: What happens if gasoline of different octane numbers is mixed?

How do I know what fuel my car has?

The fuel has a minimum octane rating in the owner’s manual and cars that require premium fuel will typically indicate this on or near the gas cap, other times it may be indicated next to the fuel gauge. If your vehicle specifies premium fuel, you’ll need to add that. Otherwise, you do not need to buy this type of fuel.

What octane number of gasoline should I use?

The best type of gasoline to put in your car is whatever octane level is specified in the owner’s manual for your model car. Typically, this is what you should know about octane gas types:

• Regular fuel is 87 octane
• Premium is 91 or 93
• The middle grade falls somewhere in the middle, it’s usually 89

To know the meaning of the octane number, the first thing we must take into account is to observe the concept of pre-ignition. Engines compress a mixture of air and fuel and ignite them with a spark. Under certain conditions, the fuel-air mixture will ignite prematurely.

This is known as pre-ignition and you will hear a knocking sound similar to that of a coffee pot. Today, almost all cars have knock sensors that prevent pre-ignition.

The octane number measures the resistance of gasoline to pre-ignition, the higher the octane number, the less likely it is to detonate. High octane gasoline has the same energy content as low octane gasoline.

• It may interest you: The best tricks to save gasoline

Does my car need premium fuel?

If your car says “premium fuel required” and your owner’s manual specifies 91 or 93 octane, you should always use that type of fuel. Previously, using low octane gasoline in a vehicle that needed premium was likely to cause damage.

Current car models come with a knock sensor that resets the engine on the fly to prevent pre-ignition, but this will most likely minimize power and fuel consumption. Showing false economy, engine damage is still possible.

Why do some cars need high octane fuel?

It is based on the compression ratio. High performance engines use a higher compression ratio to generate more power. They compress the fuel-air mixture to a smaller size, creating extra heat that can cause the fuel to pre-ignite. These high compression engines require high octane fuel which ensures that the gasoline does not ignite prematurely.

If your car comes with an engine that needs premium gas to run, it will state that in your owner’s manual. If the manual does not say so, then you can use normal fuel.

When can I use regular gasoline?

If your car recommends using regular 87 octane gasoline, you’re in luck. Well, this type of fuel is cheaper. Premium fuel will not make the engine run better or make more power. There is simply no benefit to running premium fuel unless there is a difference in ethanol content.

Regular gasoline typically has up to 15% ethanol (known as ‘E15’) and the premium option contains no ethanol. Ethanol is a less efficient fuel than gasoline, making gasoline without ethanol better in efficiency than gasoline with ethanol. However, the extra cost of premium non-ethanol gasoline over regular E15 is often much more.

Can I choose what type of fuel to use?

If your vehicle indicates “recommended premium fuel”, you have a choice: you can use regular, midgrade or premium. However, the difference may be minimal, these engines generally make more power and better fuel economy with higher octane fuel. However, it will not harm the engine or void the warranty if you use regular gasoline.

It is always best to use both regular and premium tanks and calculate your fuel economy. Considering whether the differences in power and fuel economy are noticeable and justify the extra cost of premium fuel.

What if my car says RON 95 or RON 98?

Several European vehicles specify RON 95 or RON 98Not to worry, you don’t have to buy 95 or 98 octane fuel. These are European octane numbers calculated using a different method than used in the United States. RON 95 equates to 87 octane in the US and RON 98 equals 94 octane, 93 octane fuel will suffice for the latter. RON 95 means “regular” and RON 98 means “premium”.

Purchase of fuel at high altitude

When you’re traveling at high altitudes, you’ll probably see service stations that sell low octane fuel, for example, regular 85 octane. This is based on thinner air effectively minimizing the engine’s compression ratio, so lower octane fuel is perfect.

That reasoning works with older model cars with carburetors and minimum emission systems built before 1975. Today’s fuel-injected engines, however, detect the lower oxygen content in the air and adjust. Therefore, they expect fuel of the recommended octane rating. These engines make up for low octane gasoline, up to a point.

When you drive at high altitudes, you have to go by the numbers. If your car needs 87 octane, use that if it means buying a mid grade. If your car needs premium fuel, you may not find the high-octane fuel it requires, so planning is the right thing to do.

Fuel at low altitudes. If you don’t think you can return to lower altitudes without wasting fuel, you’ll need to purchase the minimum amount you require of the closest octane rating you can find.

Try to add fuel while you still have some in the tank, the higher octane fuel will dilute the lower octane fuel effectively, so the average octane in the tank will be closer to what the car requires. Fill the tank with high octane gasoline as fast as you can.

Diesel and E85

If your car has a diesel engine, you must use diesel fuel. Diesel engines use a different process to ignite and burn fuel. So it won’t do with gasoline and refueling with gasoline can lead to some pretty expensive repairs. Almost all diesel cars say “diesel fuel only” in or near the fuel filler.

E85 is a blend of 85% ethanol and 15% gasoline.. Various models of flex-fuel gasoline cars that can run on E85 often have a bright yellow fuel cap.

A flex fuel car running on E85 is less polluting, you’ll get 30% lower fuel economy. Do not use E85 in your car unless you are sure it is E85 compatible.