You must have a different owners manual than I. Page 678 of mine states Fuel / Octane Rating / 87 or higher. 87 works nicely in mine.

 

Htony, I wanted to point out that high compression doesn't always require premium gas. MAZDA engine with direct injection doesn't require, Lexus engine with port injection requires.

 

Where does it state that Using higher grade fuel will NOT extend the life?
My 2017 Canadian manual only says "Select octane rating 87 (Research Octane Number 91) or higher."

 

After reading this thread I filled up with 93 a couple of times (I've always used 87 thus far) and I honestly don't notice a difference. Both averaged the same MPH and the car performed smoothly regardless of the octane rating. I guess it comes down to personal preference.

 

This, which gas to use, is almost a religious thing.

 

Yes it is!

I tried both and did not see any difference.

Only my dealer tells me to fill Premium from time to time to keep the injection system clean.

 

Even better, I drive with regular in both of my Lexuses and every 3-5,000 miles I throw in a bottle of Techron which costs about the same as the cost differential between just one tankful of premium over regular.

 

I've done that with my Toyotas, never had a problem with them.

 

I've never done it and like you also never had a problem.

 

It is more a question of engine performance and efficiency over time.

 

This reminds me of Fabio not believing it's butter. And spring water versus artesian water.

If there's a decrease in performance from using 87 octane gas, the owner manual wouldn't even recommend using 87. Owner manuals are very specific and it'll state that it needs 91 octane or higher, just like the RX450H and IS200t manuals. The IS200t also has a sign that says to use premium fuel next to the gas cap.

A previous poster wrote that turbo-engines need higher octane gas. That's definitely true. Using lower octane gas in a turbo-charged engine that requires premium fuel can cause engine knock. Engine knock is like the grim reaper saying hello to your car.

 

Use 87 octane in my '17 RX 350 with very good results ... usually BP because of favorable pricing in town.

 

If you drive 12K miles a year, at 20 MPG you burn through about 600 gallons of gas. So, by using regular gas instead of premium you are saving around $120 per year. Is it worth it? I don't think you can hurt anything by using regular, but there is a reason why Toyota recommends premium gas.

 

If you use as recommended a top tier regular gas (I use Exxon) which should have the proper amount of additives in the regular blend then you shouldn't have a problem. I use Techron (from Costco) every 3,000-5,000 miles just as cheap insurance. I would, however, be reluctant to suggest using it less frequently (once every year or so) since it might free up larger deposits that could impact the injectors or oxygen sensors. It may very well be a coincidence but a few years ago when I used Techron on a 2007 RX for the first time after about 50,000 miles I had an injector failure immediately after. Might not have been related, of course.

 

But, they do not in the RX350. At least, not since 2011.

http://lexus2.custhelp.com/app/answe...xus-vehicle%3F