PeeVee

I wonder if it is merely due to some emissions law from country to country. Because, in the end, the engine is the same.

Cocal

No it's not that, I've read somewhere that it's due to marketing reason for North America only because here there is a great reluctance in using premium, same thing for oil change intervals. We (in general) are only interested in spending the least to keep them running and not spend what's necessary for optimal performance & longevity, probably because we keep these vehicles for a shorter time than elsewhere in the world we get away with it. In the end we're all responsible for our own actions

PeeVee

Yes but why is premium so expensive? 15˘ per litre is quite a lot I think.

You can buy octane additive to add to the gaz tank yourself at Canadian Tire. I wonder how it compares with the price of the premium.

There's always the Thursday's premium at the price of intermediate promotion at certain chains to save 5˘ a litre.

lesz

One thing that should be considered as a part of this discussion is that the fuel recommended by an auto manufacturer is influenced, not only by what fuel grade is actually needed for the car's engine to run without problems, but also by what grade of fuel was used in EPA fuel economy and emissions testing. The auto manufacturers are required to recommend the same fuel grade that they used in the EPA testing. Thus, even if a car can run fine with lower octane fuel, if higher octane fuel was used in the EPA testing, the manufacturer is required to recommend the higher octane fuel because, even if the car will run with no problems with lower octane fuel, fuel economy may be marginally lower and emissions may be marginally higher with the lower octane fuel.

That also can be the reason why an auto manufacturer can use the identical engine in two different vehicle models, but the fuel recommendation for those two models can be different.

ravenuer

Interesting observation. Seems like Lexus is being very coy about the whole fuel thing. However, my 17 RX is quiet as a church mouse....no complaints about noise/vibration etc., and I use 87.

BTW, this was supposed to be a reply to post #138. Didn't seem to work.....

PeeVee

Same here, very quiet and using 87.

lesz

I will add a bit to what I said in my post a bit further up on this page.

I have a 2005 GX that I bought new. The Lexus recommendation for that vehicle was to use premium 91 octane fuel. In the 12 1/2 years that I have owned the vehicle, I have never used anything except for 87 octane regular fuel in it. During that time, I've never heard a single engine knock or had any other problems. The vehicle's fuel economy has remained at the same level throughout the period of ownership, and it has actually been a bit higher than the EPA fuel economy rating.

I can also note that Lexus/Toyota used the identical 4.7 liter V8 in multiple Lexus and Toyota vehicles for a period of many years. For some of those vehicles, the recommendation was to use 91 octane fuel, and, for others, it was to use 87 octane fuel. Further, there have been times when the octane recommendation changed from 91 to 87 octane for the same vehicle from one model year to the next.

Again, a major factor that determines the recommended fuel is what octane fuel was used for the EPA fuel economy and emissions testing. In the case of the GX, when the EPA testing standards changed, Lexus was able to qualify the vehicle as an "ultra low emissions" vehicle with 87 octane fuel, instead of the 91 octane fuel that they previously had needed to qualify it as an "ultra low emissions" vehicle. Thus, other factors besides what is needed to have the vehicle perform in a trouble-free manner, go into determining what fuel is recommended for a particular vehicle.

Cocal

I'm 1000% with you! We're being gouged by the gas companies and the government finds no collusion....Really?!

AbuSalem

Here in Middle east we have same manual as in Australia

i have RX350 2017
Gas tank is written Unleaded fuel only
NX200t Gas tank is written Premium Unleaded Fuel Only

But both are recommended 95

my new car now just 1k mile
I asked the maintenance engineer about use Reg
He told me you would lose mileage

i use regular (91) and give me 25 mpg
91RON = 87
95RON = 91

GSFRX350

You're exactly right - even though you guys have relatively cheap fuel premium is not promoted heavily. Here in Australia premium grades are pushed hard, particularly the top tier stuff (98 RON) and car servicing intervals are often much shorter in Australia for the same models. I don't know if the US is bit slacker with servicing or us Ozzies are stupid enough to pay more often for more services (I think the latter). Everything here is expensive - the RX350 F-Sport is around $103500 AUD (USD $82000).

DMVRX350F

One of the main selling points of the RX350 is that it runs on regular vs the required premium on the RX450H
To me, that was crucial bc I'd rather not have to deal with premium gas prices. Plus. I'm not a fan of CVT - feels too artificial for me..

3ISRC

jmtamu

87 seems to work great in ours. It's nice to not have to put the premium stuff in. Now, if only the gas tank was larger.

2008M3

What is everyone’s experience with using either 87 or 91?

Is putting in 91 really a waste of money?

DMPesso

everyone has their own opinion and will say anything to justify their choice if you read this thread. Personally, I notice a difference in the way it drives on 87 versus the 93. Try it and see for yourself. The first time I put 93 it felt like a new car, but the ECU does adjust. Anytime I try to switch back to regular gas the car was more noisy and didn’t drive as good.