Running a Car that Requires Premium Fuel on Regular Fuel

How will my 2014 Lexus IS250 that "requires" premium gasoline (91 or higher octane) run on regular gasoline (87 octane)?

[kojsav]

I've been running 87 and mainly 88 (e15) for a year now in my 2014 is350. Majority is on freeway and I have not come across any malfunction, just slight reduction of power (can still accelerate to pass cars as needed) and mpg is close to the same or sometimes even better if I drive at speed limit. I've floored a couple times with no issues.

[rcangel]

This man going 90mph and people still passing him.

[KingDrewPhilip]

Beautiful Lexus. I have an older model a 2009 IS250. I love it. I always put premium as I love her too much to put regular. I’m sure it would be fine if it was only one time and an accident.

[TonySkafidas]

Premium fuel is required not optional for this car. It is designed to run at that higher octane, the computer has to reprogram for lower octane fuel using the knock sensors, it decreases power and WILL make your engine die sooner.

[tpstulane]

If it doesn’t knock it’s ok. If you start to hear knocking you need to up your octane.

[beexiong]

Premium on a car that makes less than 200hp and isnt performance oriented is a market ploy to make manufacturers look upscale 🤣

[alexm]

So it seems like you can run regular gas in this car. You just get more power with the premium fuel. I'm considering an 2006 lexus IS250. Wondering if it would be any different on that car (it's older, but it has the same engine)

[chonig]

It seems that nobody realized that he used the gas filler nozzle to hit the 92 octane button before he started filling

[robertdodson]

Personally on a 250-350 I wouldn’t be afraid to use 89 gas but I have a 460 so I stick w the 93

[landenrich]

hey c i’ve definitely noticed a difference between gas premium is the move

[Trades]

The IS prefers premium but will operate okay on regular, though if you throttle hard the engine will pull timing & run rich, so you lose top end & your MPG is worse.

However if you tried to use regular unleaded on high pressure performance turbocharged cars (e.g. WRX STI or CLA 45 AMG) then be prepared for serious knocking or expensive repair bills.

[qxl]

Hey C's, Lexus recommends a minimum octane of 91 for the 2IS. I want to test out and use ethanol-free gas, but the closest gas station around here only carries it at 90 octane. Will this rating (90) still be ok for my 2IS?

[giG_apP_haCks_]

Some premium gas is ethanol-free. This is mostly a regional thing. If your premium was E-0 and your 87 octane was E-10, this would also cause a discrepancy like this. Did you verify that both fuels contained the same ethanol concentration?

[nickvetterneck]

You would have to actually burn at least two tanks one after another of the same product to get a better reading just tlyk and fyi

[jadennicoletta]

I know three people that have no issues in solely using 87 in their lexus😂

[bluwng]

You don't have to use Premium or Regular pick the one in between.

[qasimhaleimi]

For my prado if I put regular I have the car engine knocking in acceleration mainly

[RealTrpcL]

You put premium in the car, this test doesn’t make sense??…