Can I run 89 octane in my Lexus IS350?

Question

Will it decrease my power significantly? I know the engine might ping with lower octane since it calls for 91 or higher but would 89 make such a difference?

Answer 1

You can run it on 89 if you want to. Most experts have said that it is okay to do that unless your engine begins to act up (ie. make "knocking" noises, or jitter). Other than that, some cars will be okay with it.

I called my Lexus dealer and they said they highly advise against it because of the "premium engine" in the IS350. I have used 89/90 octane in my car and I haven't had any problems so far. So I say go for it, but I wouldn't drop down to regular. I'd stick with mid grade.

I have also heard that different gas station's gas makes a difference in the engine too. The quality of gas (BP vs. Citgo) makes a difference.

Answer 2

Yes, you could drive the Lexus IS350 on regular fuel instead of plus or premium fuel, but i wouldn't get anything lower than 89 octane, if you could get the 91 octane, anything lower and the engine will be very inefficient and your gas mileage will decrease, one reason the lexus engine is able to get very low emission rating and good gas mileage is because high octane gas means the engine is operating more efficiently and smoothly providing you with a smooth and more powerful ride, running on low octane will decrease from that because low octane gas isn't filtered as good as high octane gas and contains more "junk" in the gas. So basically, you would end up paying the same amount of money for the gas becuase of the decreased efficiency of 89 octane, so why not spend a few more dollars during fill up to get 91 octane?

Answer 3

You COULD run 89 octane, but you would be a lot better off running the 91 or higher. The ECU "car's computer brain" will adjust itself when the knock sensors detect the lower octane fuel to protect the engine. You'll loose performance out of the IS350 because of it, it's signifcance depends on how you drive.
I would never consider putting in anything less than 91 in my IS. I don't drive all that aggressively, but when a situation occurs where I need that power I expect it to be there.
Once you give up on that extra cup of starbucks coffee and decide to put in the 91 octane gas, reset the ecu by unplugging the battery so that the car will relearn everything.

If you're seriously considering 89 due to costs, you should just sell it and get the is250, because I hate to see a 300 hp sport sedan goto waste.

Answer 4

I work for Lexus, you can run 89, but don't. The car's computer will sense that the fuel mixture it incorrect for the high compression engine. This is important for the direct injection engine technology. If you run 89 octane, the computer will retard engine response in order to protect the engine from damage that might be caused by an improper fuel mixture. It is almost a requirement to run premium fuel especially in these newer high compression Lexus engines.

Answer 5

Lexus 91

Answer 6

Yes. It's going to make a big difference in performance. The 91 is better for the engine as well. Stick with the 91.

If the price was a problem why'd you buy a car that requires 91... Try driving a little less if that seems to be the problem with finances.

Answer 7

i own a repair shop and yes you can run 89 in it ,its not going to be noticeable on that one,the only thing you,ll notice is you saving money,i have customers who run 87 octane in those and they run good on it,it wont hurt it any at all,and if you don't like the way it runs,if you think its loosing power just put 91 octane back in it,its that simple to do,but it wont hurt a thing to try it,good luck i hope this helps.