justin1203

Again, if we're concerned about $225 per year (national average as you say, fine by me) after spending $40 - $50k purchasing our vehicles, then once again, get another vehicle.

Try a Highlander.

Manual does says premium fuel, and that's what I use. I don't care if running 87 produces no "so-called" ill effect. If I was concerned about the oil executives, I'd buy a Prius.

BertL

Folks, We've been here, done this discussion many times in other threads. Let's just be sure we don't begin to get too personal in the passionate points everyone is trying to make, or get too far off the intent of the original post in our comments.

Some of us consistently quote the minimum fuel rating Lexus officially suggests be used in various MYs of different models. Some owners (like myself) heed that advice in the decisions they make, the actions they take, and the cost it involves from their wallets. Others may choose to take a different approach with their own vehicles to save a few bucks because they believe they know better than the Lexus Engineers that establish the manufacturer recommendations. I say, that's fine and so-be-it. We each make our own decisions what's best for us and our own situations.

Recent sidebars in this thread contain the same sort of round-and-round points that can and have been made on the value of using dealer service vs Toyota, DIY, or a 3rd party shop for non-warranty maintenance when owning a luxury vehicle like our Lexi. Many opinions, many options. Let's now get back to the original intent of this thread please.

Johnknee

I just got my car from the auction last night and used premium and it only went down 2 bars from being at a full tank. I'll drive it more and update you guys!

budwom

FWIW my 2013 manual says 87 is fine, it runs fine on 87, can't imagine why I'd change.

naytrix

Well, so far beyond opinions no one shed light to the "87 or better" part of the question. It seems like I will have to stick with 87 for now. I was really hoping for an answer like "this engine is magically optimized for any unleaded gasoline type, so if you want more power, put 92 but if you want to save money, put 87". Alas, if I ever will find an answer I'll post it here. Thanks everyone!

Oldfart

This is exactly main misconception. Some excerpts from Wikipedia:

"Octane ratings are not indicators of the energy content of fuels. They are only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner."

"Where the octane number is raised by blending in ethanol, energy content per volume is reduced."
92 has more ethanol then 87, is it significant? of course not but how some get better mileage from lower energy gasoline?

https://en.wikipedia.org/wiki/Octane_rating

ericsan13

I think this depends on what your engine was designed for. If it was designed for premium (RX 2010-2012?) then you will lose power as the car will retard the engine to prevent knock caused by low-octane fuel.

On the other hand, if you have a car designed for regular (RX 2013-2015?), then putting in premium will do you no good. It could also possibly cause you to lose power due to higher ethanol content and therefore less power density.

While the energy density in both regular and premium is similar, how the car utilizes it is a different story.

I could be wrong but this is my understanding.

ericsan13

Also, I have been testing 87 octane in my 2010 RX for 4 months now. So far I have seen a 3.5% drop in MPG (from 19.6 to 18.9) over the same time period last year (April to July).

Since I got new tires before my switch to regular, I could probably attribute up to 2% loss in MPG to new tires. However the old tires only had 17k miles on them and the new tires are LRR tires.

So is premium worth a 11% price increase in Washington for a car designed for premium? Nope!!

-Eric

vlad_a

ECU will compensate for engine knock associated with lower octane gasoline.

Yes, RX350 is tuned to run on regular, if you will, but same statement can be made for premium, as engine timing will change accordingly based on the engine knock readings.

raylor4

Our '11 RX runs quieter on premium. No change in MPG around town. Wife likes premium. I guess that's why she married me. Sorry.

lexus114

2011 recommend premium dont they? 2013-15 do not

davew277

I'm fairly sure that my 2010 manual states that premium is recommended but regular can be used at reduced performance if premium is unavailable. I take that to mean that premium is what I should use except in an emergency.

I follow the manufacturer's guidelines. If the newer models recommend regular, then that's what I'd use.

naytrix

Ok guys! I have contacted Lexus outlining the issue. This is what the reply was:

I think I will switch to Premium from now on.

Joeb427

iTrader: (1)

and that's why I've said there was no change to the engine.
Toyota 3.5L used regular and gas cost was high when the '12 ES and RX came out and Toyota decided to go 87 with Lexus.
Can't hurt using 87 but for peak performance use premium.

RXRunner

In our 2010 RX we mix both 87 and 91 Octane fuel. I never really notice any big change in power or mileage as a result. Some of our local gas stations do not have a premium / higher octane choice.