What gas grade is required for 2018 Lexus IS 300 AWD F Sport?

Hello experts and knowledgeable drivers. I recently came off the phone with both Toyota and Lexus dealership on what gas grade is required for a 2018 Lexus IS 300 AWD F sport, and both companies gave me uncomfortable answers.

Toyota said at first regular was to be used, then they changed their mind when I told them my research showed Premium is required via google.

Lexus said regular is to be used but went on to say the choice was up to me.

Google keeps showing me Premium 91 to 93 and labled " required"

My owner’s manual is so thick I get sick from reading through those awful lot of pages.

However, I have received great help here on CarTalk in the past and this is why I am choosing to seek your help.

Thank you very much.

The best advice is to read the manual. There may also be a sticker on the gas door indicating the required fuel.


It is confusing, the owners manual states “Unleaded gasoline only”. When premium is required the manual usually states “Premium unleaded gasoline”.

However page 587 shows 91 octane or higher, that is premium gasoline.

2018 IS300 gasoline


Thank you for your reply.

On the gas tank lid, it reads E20/E85 ( I am not too sure) but what does these numbers mean?

EDIT: Given the picture of the gas cap provided by @Nevada_545, you do NOT have a flex-fuel vehicle.

The E refers to ethanol in the gasoline. The second number refers to the percentage of ethanol IN the gasoline. Normal pump gas is E10 or 10% ethanol. E85 is 85% ethanol fuel, E20 is 20% ethanol fuel. You CAN use that, if you wish, but don’t HAVE to use it and it MUST have an octane rating of 91 for you to use it.

I am not too sure about these numbers. I am away from the car as of right now. But I recalled seeing those numbers vaguely.

Thank you. Very helpful.

With the line through E20/E85 it means do not use E20, E85 or anything in between. You do not have a flex fuel vehicle. You can use E10 or E15.


One more factor-you have a high-output turbocharged 4 cylinder, which is another reason to use premium.

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fueleconomy.gov is another source for fuel requirements.

2018 Lexus IS300 fuel economy

Note that the IS 300 AWD has a V 6, no turbocharger.

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Thank you, but what does this all mean? I am still not understanding.

Does this mean E10 or E15 is premium gas or regular? I normally go to shell gas station and I only see 87/89/93

E designates the percentage of ethanol blended in to the gasoline. E10 would be 10% ethanol. E15 is 15% ethanol.

Octane is something different. You need to be putting the 93 octane in there, and it needs to have a maximum E rating of 15. Generally if gas has more than 10 or 15 percent ethanol in it, it will be clearly marked as such - either with E20/E85 or “Flex fuel only.”

You presumably spent a lot of money on this car. Do you really want to put that at risk by not reading the manual to learn how to maintain your car correctly?

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E10 is available as both ‘regular’ and ‘premium ’, as shadow fox said use the 93 octane. Some states 91 will be the highest available.

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Most gasoline sold contains 10% ethanol, both regular and premium, there is a message on the gas pump indicating the alcohol content.

Some time in the future you may see E20 at a gas station, you should not use this in your car.

Octane rating is a different subject, you should be using 91 octane or higher in your vehicle.

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Either. E10 or E15 is just the Ethanol content. Gas stations around where I live only have E10. So all grades (87, 89 and 91) octane are E10. You vehicle requires a minimum of 91 octane. So 91 or higher octane is what to use. Using a lower octane under hard acceleration could do serious damage to your vehicle.

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