Writing about Cadillacs is almost a daily practice on this blog. Today we will look at what type of gas is best suited for the Cadillac CT5. The CT5 is a relatively new car. However, this doesn’t mean the fuel requirements are all that simple. Here’s a quick answer:
Cadillac CT5 and CT5-V manufactured between 2020 – 2021 take premium gasoline with an octane rating of 93 or higher. From 2022 onwards, the CT5, CT5-V, and Blackwing have premium gasoline with an octane rating of 91 recommended.
However, this doesn’t tell us the whole story. In the article below, we’ll discuss what kind of gasoline is used for what type of engine. Furthermore, we’ll discuss different additives that can and can’t be used, what percentage of ethanol is acceptable, and the gas tank size of the different CT5 generations. Read on!
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Does The Cadillac CT5 Require Premium Gasoline?
As you already read, the 2020 – 2021 model years of the CT5 take 93 octane whereas, from 2022 onwards, this changed to 91 octane. However, there’s more to it than just that. First, it’s good to know that all these model years have the same 2.0L LSY turbo, 3.0L LGY twin-turbo, and 6.2L LT4 supercharged V8, which means Cadillac simply used a different tuning for the later model years.
Furthermore, you must know that it’s possible to use lower octane gasoline whenever the recommended is unavailable. For the 2.0L LSY, Cadillac states that 87 octane can be used temporarily. For the 3.0L LGY and the 6.2L LT4, you can go as low as 91 octane.
However, keep in mind that lowering the octane levels will diminish performance. Also, going lower than the recommended octane rating will result in engine knocking, something we’ll talk about more later. Furthermore, please ensure you’re using unleaded gasoline, as leaded gasoline will harm the engine and fuel system beyond repair.
If you’re interested in the different gasoline requirements for all Cadillacs, please read the article we just linked.
What Types Of Gasoline Can And Can’t Be Used?
Reformulated Gasoline
First, we need to discuss the use of reformulated and non-reformulated gasoline. Reformulated gasoline is gasoline that is designed to burn cleaner than non-reformulated gasoline. For this reason, it has become widely popular in many regions of the United States. It has become mandatory in many states to use this fuel.
Therefore, it’s good to know that all engines used in all generations of the Cadillac CT5 are designed to take both reformulated and non-reformulated gasoline. Consequently, you don’t have to worry about what gasoline you put in your engine (at least not for this criterion).
However, we have to say that Cadillac recommends using reformulated gasoline whenever possible. Like other carmakers, GM (Cadillac owners) realizes that this gasoline type is better for the environment. Furthermore, this type of gasoline doesn’t diminish the performance of your engine in any way, shape, or form, and it also carries the same price as non-reformulated gasoline.
Gasoline/Oxygenated Blends Or E-85
Furthermore, we have to talk about using oxygenated blends of gasoline. These oxygenated blends typically contain ethanol or methanol; both are made with bio-sources such as corn. For this reason, they burn cleaner than gasoline which doesn’t contain it. However, there are some strict rules for these types of gasoline.
First of all, all model years and all engine types of the CT5 are compatible with gasoline that contains a maximum of 15% ethanol (also referred to as E15). However, this also means that E30 or E85 (also referred to as FlexFuel) are strictly forbidden and will result in unrepairable damage to the engine and fuel system.
Also, using gasoline mixed with any percentage of methanol is strictly forbidden as this will also damage the engine and fuel system.
Gasoline With Added Materials
Typically, car manufacturers recommend against the use of fuel additives. Fuel additives are sold as octane-boosting substances or advertised to help keep your engine clean.
Boosting octane is a reasonably useless practice since it’s recommended and safer for your engine to buy premium gasoline at a certified retailer. Furthermore, cleaning additives are also advised against because they typically contain silicones or metallic, damaging the engine instead of cleaning it.
Therefore, Cadillac instead recommends using TOP TIER gasoline sold by certified retailers. This type of gasoline already has all the proper additives mixed into it, and it has been scientifically proven that it helps keep your engine clean and perform optimally. It also doesn’t cost any more than non-TOP TIER gasoline. You can find a retailer on toptiergas.com.
If for whatever reason, you don’t have access to TOP TIER gasoline sold by certified retailers, Cadillac advises you to use their own certified additive (this is a recommendation for all engine types). Cadillac sells this additive as ‘ACDelco Fuel System Treatment Plus’. Cadillac advises you to add this to your fuel tank at every oil change (every 9,000 miles). The reason for using this is that this will keep your engine deposit free and, therefore, in optimum condition.
What If I Hear A Knocking Noise From The Engine After Refilling?
Hearing a slight knocking sound coming from the engine is normal. Especially when the car is performing at peak levels, such as when towing, a slight knocking sound can be heard. However, if this knocking sound becomes very audible and happens right after refilling, you may have more significant problems.
First off, in this case, it’s very likely you’re using gasoline with a lower-than-recommended octane rating. For example, Cadillac states that 87 octane can be used with the 2.0L LSY even though 91 or 93 octane is recommended or that 91 octane can be used for the 3.0L or 6.2L even though 93 is recommended.
However, if this creates a situation where you hear a loud knocking from the engine, it’s advised to stop immediately. This knocking noise tells you the engine is misfiring because it can’t handle the octane level used. It’s best to stop your car immediately and call your dealer or garage. Your car will need to be drained from its fuel, and the fuel filter will need to be replaced. Continuing to drive will result in severe engine damage.
What’s the Fuel Economy Of A Cadillac CT5?
Cadillac has never been known as a fuel-efficient brand that uses every drop of gasoline. Manufacturing the CT5 and the CT5-V with three engine options, all equipped with a turbo- or supercharger and non of them a hybrid, is a testimony to the Cadillac brand.
However, for the average consumer, fuel economy is an essential factor. Therefore, we’ve compiled the fuel economy numbers of the CT5 in the table below. We see here that the fuel economy of the 2.0L LSY engine isn’t good, but it’s also not bad, especially for a vehicle this size.
However, when you opt for the 3.0L twin-turbo or the 6.2L supercharged V8, it becomes clear that you’re buying this car for pure gasoline performance, not because you’re looking for something that’s fuel-efficient.
| Engine | Combined | City | Highway |
| 2.0L | 27 | 23 | 33 |
| 3.0L | 22 | 19 | 27 |
| 6.2L | 16 | 13 | 22 |
What’s The Gas Tank Size Of the Cadillac CT5?
Cadillac CT5 manufactured between 2020 – 2021 have a fuel tank capacity of 16.5 gallons or 62.5 liters. From 2022 onwards, Cadillac CT5 have a fuel tank capacity of 17.5 gallons or 67 liters.
Sources
- https://my.gm.ca/cadillac/en/content/dam/gmownercenter/gmna/GMCC/dynamic/2020/cadillac/ct5/en/2020-cadillac-ct5-owners-manual-english.pdf
- https://cdn.dealereprocess.org/cdn/servicemanuals/cadillac/2022-ct5.pdf
- https://fueleconomy.gov/feg/search.shtml?words=ct5
Hi! My name is Stefan; I’m the owner and lead writer at TheDriverAdviser.com.
I’m an active writer on this blog myself, as well as a novice car mechanic. For the really technical stuff, I find writers with experience as a mechanic or who have studied mechanical engineering.
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