Yup, too many people are stuck in the 80s, 90s mindset where they need to change fluids so damn often. When people change synthetic at 5k miles, it's mind boggling lol.

 

Why you’d put 87 octane in a 306 horsepower, 11.8:1 high compression engine is beyond me.
You are losing power and efficiency. To each there own though.

 

I'm going to need both of you not to exaggerate what we are saying. No one has said that the engine is going to immediately self-destruct if you put 87 in it. You are correct in saying timing will be pulled as soon as knock is detected. It would be crazy to create an engine that couldn't make do with 87 or even 85 if you're out in the desert where that's the only fuel. However, it seems perfectly fine to tune an engine to run optimally on 91, and that's what I am getting at - using the fuel that was meant to be used in the engine.

I'm gonna be honest and say yeah, putting 91 in my vehicle did feel special for a while. "OoH, I hAvE a HiGh-PeRfOrMaNcE cAr, ThAt'S wHy I pUt Hi-TeSt FuEl iN iT!" But, GM has made a V6 that puts out over 300 horsepower on regular fuel for years. Toyota Camrys get a 300-horsepower V6 that runs on regular now. It's not actually that special. Having said that, I know that, in theory, the engine is able to perform more efficiently on 91. It's designed to run on it. Peak horsepower and torque figures as well as fuel economy figures were more than likely achieved using 91. Heck, even using 91 I was unable to match the EPA ratings during my time with the car (getting about 19 MPG overall). So, simply put, I was just trying to extract the most performance, efficiency, and reliability out of the engine by using the recommended fuel. I realize that's not for everyone, but unless you know what you're doing (which, you engineers probably do), I wouldn't recommend to anyone to use anything less than 91.

There are multiple instances of folks having transmission issues which were allegedly resolved by doing a transmission fluid exchange. I encourage you to use the search feature here and find those. I don't think "lifetime fluid" truly exists, strictly speaking anyway. It's going to degrade over time due to heat cycling and contamination. It may simply be referring to "lifetime of the transmission". So do you want to replace the whole transmission? The 3IS has not even been around long enough for any owners to know anyway.

Side note, I wasn't old enough to even read in the 80s, so not sure where that one comment is coming from. Besides, we weren't even talking about oil changes. That's a whole other topic which has also been beaten to death.

 

You're all missing the critical point that I live in Denver at 5,500 feet above sea level.

91 Octane isn't doing a *** damn thing better than 87 is. The air is too thin. It already burns TOO slow. My car is noticeably more responsive on 87, same with my old WRX, even on a tune.

Yes, 91 is better at sea level.

We're also not all fast and furious fanboys who go around stomping on the gas at every light. 300 HP in such a heavy car is NOT FAST and even so, at no point during any of my daily activities do I need all 300 HP. The power argument is moot.

 

my comment wasn’t for you, it was for the vast majority of the population that doesn’t live at elevation.

 

Yes, you are correct, altitude does play a role. Less air = richer air-fuel ratio, thus less risk of knock. However, in modern engines it might be a moot point anyway since they are dynamically looking for knock all the time and backing off the ignition timing.

Also, have you considered that maybe we just drive the cars as intended?

 

Lol, I know several engineers and they love reminding people of it. In a good way, but its hilarious, very common.

Arentz07 has summed it up perfectly.

Find you a car which died because they used 87? Find me the dip-**** driver who would actually try.

And no we're not talking about a week, or month, etc. Obviously its not going to self destruct in a short time frame. Obviously they're smart as hell at Toyota, and these are engineered with worst case scenario in mind. Pretty sure that's not lost on anyone here...regardless of their degree.

Sorry man, but really.
I'll say (non-engineer) I agree with both "sides" to an extent but let's keep it logical.

 

Premium

 

Sage advice.

 

Premium...why? Because I can afford it, and I like to take the necessary care the manufacturer suggested for all my cars.

 

I'm in western WA at low elevation, so the best premium around here is Cenex Top Tier ethanol-free 92. I always see exotic cars and historics at those stations. It's of questionable use for these high-compression Toyotas, but it's not that expensive. I've used pure-gas.org to find high-octane, ethanol-free on roadtrips. It theoretically boosts power and range by 3%, and I notice a real-life combined avg 1 mpg improvement in my 350. To be clear, its better economy doesn't offset its greater cost, but it's only another 30 cents or so per gal and it may be better for fuel systems. These cars are so sensitive to driving style that it's hard to attribute mpg/range improvements to fuel type, so take it with a grain of salt.

I sometimes also put in 2-4 gal of "Trick brand 100 octane unleaded ethanol-free racing fuel," an independently-offered product at a local 76 station near a race track. It should boost the tank octane from 92 to 96 or so. Car runs beautifully on it but it may be a placebo, and I rarely do it because that stuff is like $10 per gal.

 

Costco 93 and car burns it weekly.

https://drivers.lexus.com/lexusdrive...etails/ART2624

 

Any top tier gas, premium. In South Florida, we have 93.

 

-sweating intensifies- looking at the canadian owners manual

 

ok look, so it's like this.

I have a turbo miata that is making around 300whp or figure maybe 350 crank hp out of a 2.0L so that gets 94 octane along with methanol injection because even a tiny bit of knock will break pieces off the piston or bend a rod very quicky. Then I have a sport bike making about 185hp out of 1.0L engine that also gets premium. I have a dirt bike or two that have service intervals measured in hours for the piston and if you put even bad 91 in them you can hear them knocking.

So why do I put 87 in my IS, frankly because I don't care about it very much and I use it to commute to work where I don't know a difference if it is making 306hp on premium or 295hp on regular. I bought the car to be somewhat of a less boring daily driver but I don't worship it on a shrine in the garage and it's not the only nice object I have in my life that I spend my time obsessing over. Neither am I rich so that $500 or so saved per year on the fuel could go to the many other things that would actually make a difference. Like fresh tires on my other cars or bikes, or maybe a track day.

That's my POV with all this "respect the car you dip **** idiot" talk. The way you guys make it out is like you're all driving toyota 2000gt museum pieces and it's your moral obligation to preserve them for the future generation.