BrentBurnz

I've been driving my 2015 CT200h for about two years now, and until recently, I've always been using Premium 91 gas. I read a couple posts on other forums saying how 87 is all you need, as there is no difference.
I've then talked to Lexus Customer Service, and while he said the minimum required is Regular 87, based on their "recent research" he recommends using 91 because of fuel efficiency.

Does he actually have a point, or is it just bs? While mpg is important, it's pretty low on the totem-pole as I would assume it shouldn't make a huge difference. I'm mainly worried about the gas quality and if it'll be worse for my engine over time if I use 87. (disclaimer, I know nothing about the chemistry behind the gas and your engine)

So I'm thinking of 4 scenarios:
1)Always use 87
2) Always use 91
3) Settle in the middle on 89
4) Or mostly use 87 and occasionally use 91 (I read online that people do that too to "clean their engine"?)

Thanks.

SteveMason

The CT has the same engine as the 2010+ Toyota Prius and that engine is designed to run on regular gas. From all the research I have done, there is absolutely zero reason to use anything more than regular in this car. Other Lexus cars are a different story though. The IS and above are supposed to use premium because the engine was designed for it. The rule of thumb is if the engine was designed for regular, there is no reason to put in premium. The Prius engine is designed for regular so therefore there is no reason to use premium in the CT. A lot of taxis with the same Prius engine have run 500,000 miles+ with no issue so I feel you are just throwing your money away... However some people swear that they get more distance out of a tank of premium than a tank of regular... It would be very hard to compare though because there are so many variables that go into mileage such as highway driving vs city driving, speed, acceleration, weather... and even if the heater is on in the winter time it uses more gas.

Miamiboy87

I've always been inclinded to use premium only because it is of better quality and does help clean the engine better. Lexus even recommends just using 87, in fact they even advertise it as I saw it in one of the ct200 sale brochure. I have used 87 since I got mine back in Feb. What is interesting and may just be a fallacy is that when filling up with 87 I get about 360-370 cruising range miles. I used 91 once and noticed that I got 390! I only tried it once so it maybe that I kept pumping after the pump stopped automatically.. not sure. I'd have to test it again. It wouldn't hurt to use 91 once a month or so if that makes you feel better, besides, in all, the cost difference would be minimal, for 11 gallons at say 2.50 for 87 and 2.70 for 91 you're looking about at an extra $2-$3.. so it would be worth it.

tofuprod

Given that I live in Chicago, this is what I do for the CT
Regular, Unleaded.
Shell, Mobil, BP only. In that order of preference.

For my other vehicles as they are sports cars, I use premium as required (not just recommended).

I never spend "less" just to save a few bucks. If I buy a car but "cannot" afford the fuel in retrospect to the lifestyle I lead, then I either bought the wrong car, and/or I do not have my sense of fiscal responsibility correct.

It's a tad funny but I have a whole excel sheet at home that breaks down my DTI and expenses, I would say my gas spendings is the most variable since at times I take another car out over the other and obviously the mileage I have varies time to time depending on weather and where I drive to. The CT is a pretty fuel efficient vehicle and while I've never run premium in it, I see it in that particular motor as highly unnecessary.

BrentBurnz

Thanks for the detailed reply. Kinda sad that the engine is the same as the Prius though; makes me wonder if I should've just bought a Prius and save 10k+, haha.

Yeah, the cost is pretty negligible so it isn't a huge deal. Though if I really wanted to nickle-and-dime it, if I get 20 more miles using Premium, that's only like half a gallon, so I'd technically still save more using regular on a full fill-up.

Same, I definitely always use Premium on my BMW since it says it's required, but didn't want to waste money (albeit a very small amount) on my CT if it really made no difference. If you look at it over my ~2 year ownership, I'd save what, like $200 total if I used regular from the get-go?

RonSwanson

When it comes to the CT, there's definitely no need to get another above 87 grade gas. Also, as far as which vendor to purchase from, as long as they are "Top Tier", you're fine. I used to have a stigma toward stations like Arco, but I've learned over the years that they have the same quality standard as the more expensive stations.

Source:
https://en.wikipedia.org/wiki/Top_Ti...rgent_Gasoline

Raidin

The only reason some engines recommend premium, but can do with regular, is performance. Some manufacturers eck out every ounce of horsepower out of their engines within their budget limit, and one of the best tricks is to require or recommend premium fuel. When an engine is designed to use the higher octane fuel, it produces more power. If the car detects that you are using regular, it will change its parameters to work with regular, but at the cost of a few less horsepower.

The CT's engine doesn't generate any more power at higher octane than 87. Therefore, there's no need to use it. I don't believe higher octane is any cleaner, since the cleaning agents are the detergents, and those are added to the fuel, so it doesn't really matter. Top tier gas brands use a lot more cleaning agents than discount gas stations, so as long as you use those, your engine will run clean. You can always use fuel cleaners if you want to add more detergents to your gas.

Bottom line, as far as I'm concerned: higher octane than 87 is a pure waste of money unless your engine is designed to take advantage of the higher octane and give you more power. Our car's engine is not one of them, or Lexus would have mentioned it.

FYI: I have a Miata and a Mustang. Both of them recommend premium but take regular. If I use regular, I just lose 10 or 20 horsepower on the Mustang, and probably less than that on my Miata.

roadfrog

Speaking on the CT200 only, using anything higher than 87 octane is throwing money away. Even if you could eke out an extra 2% fuel economy, you're going to be paying more than that in the fuel price difference. There are TONS of papers and studies that have beaten this one to death.......use 87 octane. My LS460 requires 91 octane, and using lower octane reduces power a bit...it's noticeable. But it's a 390 hp V8 tuned to run best with 91. Running 87 won't hurt it, as the computer will retard timing when the knock sensors hear a ping, but I like full power from my LS! As for detergents, if you use on of the many "Top Tier" gas companies (most are), you'll get detergents regardless of grade, The only caveat to this is ethanol. If you can get non ethanol fuel in a higher octane...I'd do it. Ethanol is pure evil.

E46CT

87 only. Nothing higher in this car. Ever. Will hurt mileage, not help.

14ct200h

Ditto.

Same engine as the 3rd gen Prius, no need anything higher than 87.

E46CT

yep. and same goes for any commuter 4 cylinder. i think the word "premium" is a marketing trick that fools people into thinking it's a better quality gas. All it means is it's more resistant to ignition =)

Raidin

There's a lot of stuff online on this if anyone decides to research it, but here's a good one, straight from the US Federal Trade Commission:

https://www.consumer.ftc.gov/article...ctane-gasoline

Quote from above link: