Lexus CT200h Forums banner

Best Gas for 2011 CT 200h

8.1K views 7 replies 7 participants last post by  Pete44  
#1 ·
Can anyone answer the proverbial questions regarding not only which is the best octane level of gas for the Lexus CT 200h, but what brand of gas works best for optimal mileage and why? The manual says 91 octane, but the dealer says 87 is perfect for all four cylinders and anything more than this is just wasting money; and other Lexus owners are cringing that I would anything less than 93 in the car. Also which brand of gas works best? The oder from best to worst that I have been quoted is Sunoco > BP > Chevron > Mobile > Shell and that unbranded gas is BAD!!! Incidentally I am getting 40-42 mpg and an occasional 44 mpg using only premium (using AccuFuel app on an iPhone to calculate - 2 mpg less than the number given by the car gauge), but find it hard to get to the "better" branded gasolines. Finally, how much of a decrement in non-mpg performance (i.e. pick up, top speed) can I "expect" if I use only 87 octane; or stated differently, can I "expect" to get significantly better non-mpg performance by always using 93 octane?
 
#6 · (Edited)
The powerplant of ct200H is a Tianjin (Chinese) made 1.8L Atkinson variant 4 cylinders dohc 4 valve/cylinder normally aspirated fuel injected engine, it is a low compression high rpm engine, therefore AKI rating is not an issue. There is a range by which the built in sensor will self adjust timing to eliminate "knocking". Remember in the US the gasoline rating is based on AKI (anti knox index) while most of the rest of the world uses RON (research octane number). The AKI value is typically lower than RON. PS: In the old days, I used to retard my timing mark whenever I buy a load of cheap gas. I shined the timing strobe on the flywheel and retarded the timing mark by carefully listening to the engine "knock" disappear ... Yes, it is totally unscientific but it worked!!!
 
#7 ·
I have a 2012 CT200h in Canada. I bought the car new 22 months ago and have 80 000 km. My dealer told me to use regular fast (87). The octane level has no bearing on fuel efficiency. The best advice i have received has been to take it in for regular servicing at the scheduled time (every 8000 km). To ensure even higher than rated fuel efficiency do not accelerate aggressively and keep track of your odometer meeting every time you fuel up to determine you car's fuel consumption rate.

I am frequently consuming at a rate of 3.8L - 4.9L / 100km
 
#8 ·
87 octane is book recommendation (2013 CT). In high altitudes (Colorado) lower octane is sold as the "regular". For example, 85 octane is the lowest in the mountains here (Montrose, CO). This is because with higher elevation, there is less oxygen getting into the engine, and it is even harder to have premature ignition or detonation ("knock"). I manage aircraft engines, have built race-car engines, and am currently building a fully electronic engine system, which adjusts the timing like a car does, for an experimental aircraft. I have successfully made 1000 hp at the wheels (car) from a 2.0 liter engine. So this is with some consideration, research, and an undergraduate degree in chemistry that I will say the following:

Use "regular" gas wherever you are (lowest octane...usually 87). If the lowest octane is 86 or 85, use that. Lower octane fuel is slightly MORE explosive than higher octane numbers, and will possibly give you a slight bit more power per stroke, but certainly it will save you money. Your engine has knock sensors which will change the timing to protect the motor. Should you get 85 octane, for example (in high elevations)...then drive to sea-level and floor it, you might get some knock. You'll have to be pushing the engine to get knock, but likely could get significant knock in that case...particularly up a hill. If you manage to get significant knock (almost impossible in these engines with good fuel) you'll lose mileage and efficiency because the timing will be changed to eliminate the knock) this will give you less efficiency but protect the engine.

The detergent additives in "top-tier" gasolines are added after refineries produce the fuel. Chevron has Stoddard Solvent as part of their additive package. Others don't, from what I understand. All top-tier gasolines have additive packages, with "detergents" which are designed to keep the engine clean, particularly the fuel injectors. I have been told by a knowledgeable old-time race-car builder/racer that Chevron's "Techroline" additive is better than the others. I have my doubts, but don't know. I've been using top-tier gasolines mostly, but paying more attention to doing so now. I guess I'm finding that I'm wanting to go to Chevron more (because of this man's poisoning my brain), but I have a strong suspicion that Shell/Mobil are just as good with their solvent packages and that any top-tier gasoline (most of the big brands...you can look up a list, but they won't include your grocery store, Sam's Club, etc) will be equal.

Please comment if you happen to have any specific information on these additive packages.