The owners manual states to use 91 octane, I suppose that is a recommendation, not a requirement but what does it show on the fuel door? Is that just a suggestion?
This is the fuel door on a ES 350 in the parking lot;
The entire matter seems simple to me: use the correct fuel for the engine as specified by the manufacturer. I have a rototiller with a 2 stroke engine that specifically calls for a 50:1 mixture. I found out that it starts better if I purchase ethanol free 50:1 mixture that comes in a 1 liter can and is rated at 92 octane. Yes, it costs more than buying two stroke oil and mixing it myself in the proper ratio. My garden is small so the extra cost is worth it. My snowblower also has a two stroke engine that requires a 50:1 mixture. I use the same expensive premixed fuel in it. I donāt have a long driveway and can do my driveway and sidewalk in less than half an hour. Had the cost of the two stroke fuel bothered me, I would have purchased 4 stroke equipment. However, I prefer the lighter weight of the two stroke equipment
With a vehicle, I certainly look at the type of fuel required before I make a purchase. I wonāt buy a vehicle for my everyday use that requires premium fuel. On the other hand, if I decide to purchase a Mazda Miata for pleasure driving on weekends, and it requires premium gasoline, that would not enter into the decision as to whether or not to purchase the Miata. (Unfortunately, Mrs. Triedaqās opinion as to whether or not a 77 year old man needs a Miata carries weight). In the meantime, I have to be satisfied with my tiller and snowblower that require expensive fuel.
I heard the theory that premium fuel, even in an engine that didnāt require it, would allow the computer to advance the timing and give better mileage. On a road trip, I accidentally filled the tank of our Toyota Sienna with premiumāI grabbed the wrong hoseāand it didnāt make any discernable improvement in the mileage. On the other hand, I turned up the 1971 Ford Maverick with a 250 cu in 6 that I once owned and set the timing a little high. When I went on a road trip, I was getting spark knock on acceleration. I took it easy on the pedal until I was down to half a tank and filled up with premium. The mileage and performance were much better. It was a toss up back in the late 1970s whether it was more economical to leave the spark timing advanced and use premium or retard the spark and use regular. There wasnāt a huge difference in price per gallon as there is now, but I finally retarded the spark advance and went back to regular.
What year is the ES-350?
My wife uses high-octane. But has on occasionally used regular. I use regular on my highlander with same engineā¦but the Highlander does not require High-Octane. Not sure what the change was
The picture is of a 2007 ES 350 fuel door.
2007-2010 are listed as premium fuel, this is from the list of technical changes for the 2011 ES 350;
4. 2GR-FE Engine
The ECM software has been modified to allow the use of regular unleaded gasoline.
This surprised me on the new Infiniti QX50 fuel door. I spoke to Nissan this week and asked them if that same engine requires Premium in the new Altima, which also has the new 2.0-liter variable compression engine and the surprise answer was 'No, it does not need premium in the Nissan branded vehicle." So the changes to make it safe must be possible.
Did you ask Nissan what the difference between the QX50 and Altima versions of the engine are?
They did not. The person I spoke to was not the technical resource, but rather the model manager, so I didnāt take that next step. Iāve seen this before with other automakers, but it is usually a difference between a āRecommendedā vs. Required engine. I think it is marketing. They want to advertise the higher hp number on the Infiniti.
+1
Iāve owned three vehicles with OBD-II, and the CEL lit up only on the second oneāa 2002 Outback.
I drove to the dealership immediately, and they got me back on the road in less than an hour by replacing the Evaporative Emissions Purge Solenoidāunder warranty.
In a total of about 350,000 miles of driving those three OBD-II equipped vehicles I have spent zero dollars on repairs as a result of the CEL.
Whatās the cause and recommended fix?
On the other hand many people see those items and see features and benefits that make their driving experience more efficient and enjoyable. Not everyone wants to drive a base-model stripped down car.
Itās a long story, but the short version is that I either need a new catalytic converter, new oxygen sensors, or I need to find out why my air/fuel mixture is too rich. Iāve tried replacing the cat and the sensors, and thatās where I gave up after the muffler shop that installed the car said, āwe donāt guarantee the check engine light will be solved.ā If he had told me that in the first place, I wouldnāt have let him replace the cat.
Ahh, I see. Some people canāt live that long without getting the car repaired. If you have emissions testing, having a check engine light on is a fail.
Iāve had poor results with some brands of aftermarket catalysts. Not saying thatās the problem you have. Just my experience.
When I was younger, I heard that any car could benefit from using premium fuel, and that there would be a slight but noticeable improvement in performance and fuel economy. My dad told me that was a bunch of bull, and that only āhigh-performanceā models which specifically required premium fuel could benefit from it.
At the time, we had a 1988 Toyota Corolla, 1991 Toyota Tercel, and 1991 Toyota Camry with the V-6 engine. None of these cars ran any better with high-octane fuel. This was back in the late 1990s to early 2000s, and we only used brand-name fuelāMobil, AMOCO, or 76.
Iām curious about what is the reason for the big difference in gas prices in USA (regular - premium)
Here the diff. is 1 - one - cent and the biggest diff. I have been able to find in Europe is a tad under 2 cents/liter. That equals around 4 to 8 cents a gallon.
Mind you, we have 2 choices - 92 octane or 95.
If we can have that little diff., then why canāt you over there, one would think, but maybe there is a logic explanation.
In my area, the price differential is currently about 40 cents per gallon, but I couldnāt tell you authoritatively why the differential is that large.
Thatās steep, but why the big diff. USA versus Europe?
Thatās what Iām wondering about.
Are the fuel industry just greedy (guess I know that answer,. but) or are there another reason?
All I can imagine is that it is the same reason why dogs lick their nether regionsā¦
Because they canā¦
2 Likes
Itās $0.30 between each grade here, so $0.60 between regular and premium.
Is the sky blue?? 
Not true. This adaptation only occurs in reverse, in response to input from knock sensors, in engines where mid-grade or premium are recommended.
Where I live the difference is 40 cents each jump. Why is there a huge difference? Because they can. As long as people are paying for itā¦then the price difference will be high.