kerplunk38

For what it is worth Edmunds did some research and published some lists that show which vehicles "Require" vs "Recommend" premium fuel. The GX is on the "Requires" list.

The problem isn't short-term impact. The engine system will adjust for sporadic changes in octane. It's over the long-term that you may have issues. I purchased the vehicle knowing I needed to splurge for the premium fuel. The cost is negligible to me. YMMV.

http://static.ed.edmunds-media.com/u...red.032714.pdf

http://static.ed.edmunds-media.com/u...ded.032714.pdf

Iownit

I have a GX 460 and have been using premium unleaded as per the manual, but I have been told that you can use a lower grade. How about the medium octane? Do any GX owners have any experience with this? I know that when I owned an RX I used regular unleaded and never had a ping. When I sold it, the engine was still perfect.

Eppieguy

There is a thread on this within the past couple of days, bottom line is yes, you can run a lower octane, the computer will compensate for the lower octane and you should have no issues.

jtrue28

Just expect lower MPGs. In the end, it's likely a wash. Spend less for gas, but fill up more often...

Craig B

It will retard your timing, give you less power, less MPG...

Iownit

Thank you for your responses. I think I will have to experiment and see what works best for me. I am currently trying the medium grade for normal use, and I see no difference between that an premium. I will probably use the premium when pulling my travel trailer however.

Joeb427

iTrader: (1)

Why bother for about a dime a gallon?

UtahUtes

I wondered the same thing when I was shopping. In my research, one of the best responses was "if you are going to spend $55k+ for a car, you shouldn't be worrying about an extra few dollars per tank".

I just fill it with premium, it isn't worth the time and effort to experiment.

jmoney6

first off, I knew going in mpg would not be great however I'm currently averaging 13.8mpg. Car currently has 400 miles on it. Will this improve after the car learns my
driving style and breaks in? I don't romp on it, normal mix or city and highway driving

Reason i ask is I was expecting at least 17-18mpg average.

caesosa

I think it will. Mine has 73k on it and my wife gets about 15mpg and never gets on the highway which isn't good but at least expected (with AT tires on). When we do get on the highway we see a significant jump to 18-19.

It will probably be until after 2,000 miles before you see it get to normal.

Oldmanb777

Probably not much. after the difference between stop and go city, vs highway, then driving style is the BIG factor. A few years ago when gas prices were high. there was a magazine article,(I think in Money Mag) about how much gas was wasted by poor driving habits. They took some average drivers, put them in identical cars. The results were staggering. Almost 30% as I remember it. On our previous car, my wife would be doing good to break 11 mpg, I could get 14 mpg all day long, driving the same route with the same car. She doesn't drive fast, or try to race everybody. It's more about planning your acceleration, and stopping, etc. Ever notice.................If you take your foot off the gas, the car doesn't slow much in the next block,before you have to step on the brakes to stop at that stop light. FREE gas mileage. And less brake wear, less tire wear ETC,ETC,ETC Total benefit. Lots more to that story. But hope you do better after you get used to the quirks of the car.

hzhao

I agree what Oldmanb777 said here. With today's technology, "Break-in" term has changed a lot. Driving habits contribute large portion of actual gas efficiency. Other big part would be the driving conditions, such as road, traffic situation, etc. Not sure if GX engine management system is a true "adaptive" one, that adjusts drivers input. It is certainly tuned for "heavy truck" type, considered its the same engine was in LS but removed direct fuel injection, and replace with six speed tranny instead of 8. Its not torque happy than racer. We used most for city driving with daily routines, its at about 16 mpg. The last long trip (350 miles highway, with 70 mph speed in constant traffic flow), it gets about 21 mpg. Ours is 2014 GX and had about 20K miles on the car since bought in April 2014.

rroman001

My 2017 is about 4 months old and I have 7800 miles on it. My Avg since purchase is 17.6. I often achieve 23 - 24 on the highway with no traffic and leveraging cruise control set at 65. I do focus on slower accelerations, coasting before red lights, etc. Other than that, I chive it hard at times too

NewB2Lexus

Does anyone remember when the gas prices were $4+ a gallon and people driving Tahoes, Suburbans and F350s were complaining how expensive gas was? Not sure why anyone would buy a $60k, 8 cylinder, 5 ton vehicle and expect it's fuel economy to be like a civic's. There are plenty of sedans available at the Lexus dealer.

jmoney6

Where I live in NorCal, the difference between 87 and 91 can be $.50-$1.00 per gallon difference. If I use 87 instead of 91 could it really cause an issue?
Also will 87 vs 91 show a major difference in MPG?