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Types Of Gas A Lexus RX450h Takes (Explained)

Types Of Gas A Lexus RX450h Takes (Explained)

On this blog, we do a lot of research regarding specific questions about different cars. Today we’ll look at the Lexus RX450h and answer what kind of gas this car requires. We’ve gone through the owners’ manuals of the 2009 – present-day RX450h to find the answer. Here’s a quick answer:

All generations of the Lexus RX450h use premium unleaded gasoline with an octane rating of 91. However, 87 octane can be used in some model years when 91 octane gasoline is not available.

However, that doesn’t tell the whole story. Below we’ll dive into what kind of gas this car takes. We’ll talk about reformulated gasoline, E-85, and gasoline with additives. Should or shouldn’t you use this for the RX450h? We’ll also talk about the fuel mileage of each generation as well as possible knocking noises and so much more. Read on!

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Infographic explaining the different fuel types for a Lexus RX450H

Details About The Octane Rating Of The RX450h

As we already stated in the introduction, 91 octane unleaded gasoline is preferred for all generations of the RX450h. However, there are some cases in which 87 octane unleaded gasoline can be used when 91 octane is not available.

This statement holds true for the 2009 – 2016 model years, which can run on 87 octane temporarily. However, the model manufactured from 2017 onwards can’t and shouldn’t use 87 – 89 octane gasoline. This will result in engine knocking, which we’ll discuss later on.

Furthermore, instead of choosing 87 octane when 91 octane is not available, we advise you to fill up with a more premium gasoline such as 93 – 95 octane. This is because higher octane gasoline will never pose a threat to the engine and fuel system, whereas lower octane gasoline will have a risk of doing so.

On the other hand, we don’t advise you to always fill up with more premium gasoline than recommended. Some people believe that 93 – 95 octane is always the better choice, even if 91 octane is recommended. However, this is not true because the engine isn’t designed for higher octane gasoline and therefore won’t be able to benefit from it in any way.

What Types Of Gasoline Can And Can’t Be Used?

Besides knowing the proper octane levels, there are several other things that you should be aware of concerning the gasoline you use in your RX450h. These mainly include different kinds of additives used in the fuel.

Reformulated Gasoline

First, there’s the use of reformulated gasoline compared to non-reformulated gasoline. Reformulated gasoline is gasoline that’s become popular over the past decade because it burns cleaner than its counterpart. For this reason, it has even become mandatory in some areas of the United States.

Therefore, it’s good to know that Lexus recommends reformulated gasoline for all of its vehicles, including the RX450h, RX350, and others. Its use won’t negatively affect the engine or decrease its performance. Overall, it’s just a better type of gasoline that should be used whenever available.

Gasoline/Oxygenated Blends Or E-85

Another essential part of the gas we need to talk about is the use of oxygenated blends such as ethanol, methanol, or MMT. These chemicals can be added to gasoline to make them burn cleaner. As Lexus states in their owner’s manuals, the use of these kinds of gasoline is advised because it’s better for the environment.

However, there’s a limit to the percentages you can use in each generation of the RX450h. For example, RX550h made in or before 2014 can take gasoline with a maximum of 10% ethanol. However, RX450h made from 2015 onwards can handle gasoline with a maximum percentage of 15% ethanol.

This means that, depending on the generation, the RX450h is compatible with E10 or both E10 and E15. On the other hand, it also means that other popular ethanol blends such as E30 (30% ethanol) and E85 (51 – 83% ethanol) cannot and shouldn’t be used. The same is true for mixtures that contain methanol or MMT; these cannot be used at all.

Using ethanol in a percentage that exceeds the limits, or using methanol or MMT in any amount, will damage the engine and the fuel system, and this kind of damage is not covered under any warranty.

Gasoline With Added Materials

Finally, we have to talk about additives in these types of gasoline. As a general rule of thumb, just using any additive marketed to you is a bad idea. This is because many aftermarket additives contain elements that are harmful to the fuel system and engine.

These elements are most likely going to be some form of silicon or micro metals. Even though many additives are supposed to clean your engine, many will harm your engine. Also, octane boosters are advised against since it’s better to immediately tank the proper octane levels.

To prevent you from figuring out what kind of additives are good or bad, it’s best to buy gasoline from certified TOP TIER gasoline retailers. Lexus, like many other carmakers, actually endorses buying this gasoline. This is because it already has all the proper additives mixed into it, and it has been proven to clean the engine and improve the lifespan of the engine. Visit to find a retailer near you.

What If I Hear A Knocking Noise From The Engine After Refilling?

Hearing a knocking noise in a car is a normal occurrence. However, it’s essential to listen carefully to the loudness of the knocking noise. A slight knocking noise is normal, especially when the car achieves peak performance (such as when towing or driving up a hill).

However, a loud knocking noise is a problem, especially if you refilled the car. In this case, you’re likely using gasoline with a lower than recommended octane level, and the car is not handling this well.

In this instance, the best thing to do is stop the car and call your dealer or garage. It’s very likely the car needs to be drained from its fuel, and the fuel filter will need to be changed. Ignoring the knocking noise will result in severe mechanical damage.

Also read: 6 Common Problems Of A Lexus RX450h Hybrid

Does the Lexus RX450h Have Good Gas Mileage?

As one of the final aspects, we think it’s a good idea to discuss the fuel economy of this car. After all, it’s a hybrid which means many people will buy it based on its fuel-efficient properties.

What we learned while doing our research is that all generations of the Lexus RX450h make use of a 3.5L engine. There are slight differences between the fuel economy of an FWD and AWD version. Furthermore, the fuel efficiency has changed slightly through the years, although it hasn’t changed as much as we would have expected it to be.

All generations of the Lexus RX450h have a combined fuel economy of 28-30 miles per gallon. Furthermore, they reach an MPG between 29 – 32 in the city and 27 – 28 on the highway.

What’s The Gas Tank Size Of A Lexus RX450h?

All generations of the Lexus RX450h have a gas tank size of 17.2 gallons or 75 liters. Assuming an average price per gallon of $4 it costs $68,80 to fill up an RX450h.

Also read: Lexus RX 450h Towing Capacity: Can It Tow A Trailer, Boat, Or Jet Ski?


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