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The Types Of Gas A Cadillac SRX Uses (Explained)

The Types Of Gas A Cadillac SRX Uses (Explained)

The SRX was first introduced in 2003 as a 2004 model and discontinued in 2016. All were gasoline models, with none produced as diesel engine variants. Today we will try to answer the question posed in the title and tackle some other SRX related issues such as fuel requirements based on engine type, types of gasoline, what to do in case of engine knock, etc.

The 2004-2009 models had two engine types; a 3.6 L V6 with the recommendation for unleaded gasoline with an octane of 87 and a 4.6 L V8 with a recommendation for 91 octane level gas. The 2010-2016 models had three engine options; 2.8 L V6 with 93 octane level premium gas recommended, 3.0 L V6, and 3.6 L V6, which had regular unleaded 87 octane recommended, but a cleaner blend E85 can also be used in the 3.6 L option.

We will take a detailed look at the available gasoline types to understand the benefits of using the right fuel type for an engine or, conversely, the consequences of using the wrong fuel type, what octane rating means, and the latest improvements in gas blends. Finally, we will look at some fuel-related facts and stats for the Cadillac SRX.

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Also read: How Many Miles Can A Cadillac SRX Last? (Answered)

Fuel Requirements Based On Engine Type

Before we discuss the fuel requirements of each engine type, it is relevant and essential to understand what octane rating is, how it is calculated and how it affects the car’s performance. Most of us have heard the terms regular unleaded, premium, E85, E87, etc., concerning the quality of gas, but hardly anyone understands what these terms mean.

Octane rating or the anti-knock index indicates how much the gas can be compressed before it detonates. Higher the octane rating means higher compression and a more considerable detonation. With a higher octane rating, there is less likelihood of explosion happening at the wrong time, which means max energy transfer.

Engines with high compression ratios or turbochargers often require high octane fuel found in premium gas for optimal performance and fuel efficiency. However, the majority of cars on the road today are optimized to run on regular gas. Using premium gas when regular gas is recommended will have no performance benefits, although it will bite into your wallet.

Using regular gas when the premium is recommended causes severe engine knock. Engine knocking happens when fuel burns unevenly and those shocks go off at the wrong time. The result? An annoying noise and potential damage to your engine’s cylinder walls and pistons. It may also result in lower fuel economy and lower engine life.

Also read: The Drive System A Cadillac SRX Has (Explained)

First Generation (2004-2009)

Manufactured between 2004-2009, the first-generation SRX had options for two engine types; a 3.6L / V6 and a 4.6L/V8 configuration. The 3.6L / V6 engine was designed to use regular unleaded gasoline with an octane rating of 87. More about octane rating later but a higher octane rating means better quality gas. The larger 4.6 L engine with AWD required more power; hence the recommended fuel type was a 91 octane rating for optimal performance.

Second Generation (2010-2016)

Although there were quite a few changes from the first generation to the second generation, the difference in engine specs was a major one impacting SRX. The 4.6L was discontinued, and 2.8L / V6 and 3.0L / V6 were introduced instead. Whereas Cadillac recommended regular unleaded fuel for 3.0 L and 3.6 L, a cleaner blend E85 can also be used in the 3.6 L option. The smaller 2.8 L engine was turbo-charged and required premium gas with an octane rating of 93.

Also read: Cadillac SRX Towing Capacity: Can It Tow A Trailer, Boat Or Jet Ski?

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

To meet stringent emission regulations, petroleum refineries produce cleaner and more efficient fuel blends that give better mileage and clean the engine, thus resulting in lower carbon emissions. Additionally, there is a drive to introduce more eco-friendly biofuels.

Reformulated Gasoline

To control sulfur content in gasoline, EPA developed regulations in 1999 that sought to reduce sulfur content to 80 mm max in gas through the Reformulated Gasoline (RFG) program. RFG is, therefore, a cleaner and efficient gasoline blend. RFG is mandatory in cities with high smog levels and is optional elsewhere.

RFG has been shown to reduce smog levels and toxic pollutants in the environment. Along with other measures, it is contributing to bringing down smog levels in the U.S. Cadillac allows the use of reformulated gasoline if it meets the standard outlined in the owner’s manual for a specific fuel type.

Gasoline / Oxygenated Blends Or E-85

Chemical compounds that contain oxygen as part of their chemical structure are said to be Oxygenated. Oxygenates sourced from alcohols and ethers are added to fuels for complete combustion and reduction of carbon monoxide and soot created during the burning of the fuel. 

One of the most popular oxygenated blends is E85 or Flexi Fuel. It is formulated with 85% ethanol and 15% gasoline. It has its advantages and disadvantages, which are given below:


  • It is eco-friendly because ethanol burns cleaner than gasoline.
  • The biggest advantage is that vehicles that use Flexi-fuel are designed to burn whatever proportion of the mixture is in their combustion chamber.
  • Owners of Flexi-Fuel vehicles get a tax credit for the usage which substantially reduces the tax burden.


  • Since ethanol, which is used in blended gas, comes from corn and sugar, any crop used for extracting ethanol loses its agricultural use.
  • Ethanol can cause corrosion and damage to the engine.
  • Ethanol is also not as economical as gasoline with lower miles per gallon compared to conventional gas.
  • When the ambient temperature is above 90° F (32° C), the car experiences hard starting and rough idle following startup even if the above recommendations are followed.

To find out whether your vehicle is designed to run on Flexi-Fuel, take a look at your car’s gas cap or the fuel gauge on the car’s dashboard. Cadillac does not recommend any oxygenated fuel that contains ethanol over 13%. This means that Flexi-Fuel, which has 85% ethanol by volume, has way too much ethanol and should not be used in SRX.

Gasoline With Added Materials

Additives to gasoline are not something new. Gasoline additives to enhance performance have been used commercially in the USA since 1923 (source). Additives, such as alcohols, ethers, benzenes, and kinds of paraffin, are portrayed to enhance fuel quality and help boost engine performance or health.

Although the jury is still out there regarding the benefits of fuel additives, they remain popular with car owners. Here’s is why.

  • Boost Octane Levels.
  • Engine Maintenance.
  • Smooth ride for diesel engine cars.
  • Economical in terms of cash and mileage.

Does Cadillac Recommend Fuel Additives?

The following is from the SRX owner’s manual.

“To help keep fuel injectors and intake valves clean and avoid problems due to dirty injectors or valves, look for gasoline that is advertised as TOP TIER Detergent Gasoline. Look for the TOP TIER label on the fuel pump to ensure gasoline meets enhanced detergency standards developed by the auto companies. A list of marketers providing TOP TIER Detergent Gasoline can be found at”

The manual guides on which types of additives not to use. For further info, refer to the manual.

Gasoline With MMT

MMT or Methylcyclopentadienyl manganese tricarbonyl is used as an octane enhancer in gasoline produced by Afon Chemicals. MMT is allowed in U.S. gasoline at a level equivalent to 1/32 grams per gallon manganese.

Studies conducted on vehicles in which MMT was added to the gasoline showed that it resulted in several issues such as plugging monolithic converters, increased hydrocarbon emissions, and caused excessive spark plug deposits.

MMT seems to have more downsides than any substantial advantage and hence not recommended by car manufacturers, including Cadillac. The following is taken from the SRX owner manual.

“Some gasoline that is not reformulated for low emissions can contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); ask the attendant where you buy gasoline whether the fuel contains MMT. We recommend against the use of such gasoline. Fuels containing MMT can reduce spark plug life and affect emission control system performance. The thermal function indicator lamp might turn on. If this occurs, return to your dealer for service.” (source)


What is Biodiesel? It is a class of fuel formulated from such materials as recycled cooking oil, animal fats, soybean oil, or yellow grease.

Blends of biodiesel and conventional hydrocarbon-based diesel are most commonly distributed for use in the retail diesel fuel marketplace. Much of the world uses a system known as the “B” factor to state the amount of biodiesel in any fuel mix.

Blends of 20% biodiesel and lower can be used in diesel equipment with no, or only minor modifications, although certain manufacturers do not extend warranty coverage if these blends damage the equipment. Biodiesel can also be used in its pure form (B100) but may require certain engine modifications to avoid maintenance and performance problems. The ASTM D7467 specification covers the B6 to B20 combinations.

It has found wide usage in vehicles, railways, aircraft, as heating oil, to clear oil spills, and in biodiesel generators. Since SRX was not manufactured with a diesel engine, so there are no recommendations related to it.

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

Knocking is the result of uneven burning of fuel in the cylinders of a car. It is caused by using low octane fuel, faulty spark plugs, or carbon deposits. The point to note is that low-quality fuel can harm spark plugs and cause carbon deposits. So it is essential to use gas with recommended octane levels and one that has engine cleaning agents.

You are advised to refer to a qualified motor mechanic if the knocking gets worse over some time. Failure to do so may result in your warranty becoming void.

Also read: 12 Common Problems Of A Cadillac SRX

Does the Cadillac SRX Have Good Gas Mileage?

In this section, we tabulate the fuel economy data for the various SRX versions. We will give figures for the 2WD version. The values for AWD are about 1 MPG lower. The combined MPG is 55% of City MPG and 45% of highway MPG. Note: All MPG figures are for the 2WD option, which has a slightly better economy rating.

First Generation (2004-2009)

EngineMPG CityMPG HighwayCombined MPG
3.6 L / V6152318
4.6 L / V8132016

Second Generation (2010-2016)

EngineMPG CityMPG HighwayCombined MPG
2.8 L / V6152218
3.0 L / V6182521
3.6 L / V6172419

Also read: The Oil Type, Weight, And Capacity Of A Cadillac SRX

What’s The Gas Tank Size Of A Cadillac SRX?

The first-generation Cadillac SRX has a fuel capacity of 20 gallons, equivalent to about 76 liters, while the second generation has a fuel capacity of 21 gallons or about 79 liters.

How Much Does It Cost To Fill Up A Cadillac SRX?

In California, one gallon of regular gasoline is $4.388, while in Mississippi and Texas, that same one gallon costs you about $2.816. So you would have to spend $97.32 for a full tank in California. When you are in Mississippi or Texas, you would be paying somewhere around $59.14. So overall, you would be spending somewhere between $59-$100.

Based on the average price of gasoline in the USA, it will take about $70.78 to fill the first-generation SRX, while it will cost $74.32 to fill a second-generation SRX. The price used is for mid-grade gasoline, which on 27/09/2021 was $3.539 per gallon (source).


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