I think it's ok to use 89 octane gas (at the time SC was designed, there probably wasn't any 93 octane gas). It doesn't affect the engine reliability if you don't rev yours too high. High rev engine requires premium gas for pricise burning. Lower rate gas burns more violent, and can be out of synch.

I don't know where I got this information anyway ...

 

The 91/93 recommendation isn't needed for much of which what we would call 'normal' driving. It is at the engine's limits in hot weather that you will notice the difference. If you never drive your car hard, 89 will probably make no difference to you. But your car knows it and adjusts accordingly. Also, on the older 250hp engines the compression is much lower. It would probably take some very low gas of 85 or so to notice any knocking. On the 290hp+ models, the interference design raises the compression. I'd take notice of how hard I drove the car with less than 91 in the tank.

 

I don't drive my car hard at all and it doesn't knock with 89, so I use that. If I were to drive to Vegas with the heat, etc., I would fill with 91 octane.

 

both my lexus cars on on premium and gas can hit 5.00 a gallon and i'm still sticking with the good stuff

 

I drive an '06 es330 and it says right in the manual that you can use regular gas over premium gas but to expect less hp using regular. Thats the reason why the SAE numbers dropped because the hp had to be calculated using regular gas. I use regular gas and every time i get an oil change(~5,000miles) i put in a $0.99 fuel injector cleaner(preferably esso or mobil) and have always have great results doing this.

Dawg

 

OK.....i think the guy talking had the 1992 SC? I'm sure its not worth 50-60 K anymore, and EVERYONE is feeling the pain at the pump right now.

 

double post ********

 

Not sure if you were referring to me or not but anyway, I just checked my window sticker from the original purchase in 1992 (yup, I still have it.) and the full price for the SC400 was $42,120.00 before sales tax. I don't recall exactly but I think I wrote a check for something like $44,000 including tax, license and the installation of the Lexus cell phone mounted in the center armrest and wired through the sound system and the hands-free buttons on the steering wheel. That was about a $1,500-$1,600 add-on that I got the dealer to throw in to make the deal. So, it never was $50-$60 K when I bought it and with 353,000 miles I doubt its worth more than $4,000 or $5,000 now if I tried to sell it. Though premium gas is needed for maximum performance from the 250 HP engine, I hardly thnk that using 89 ocatane is in any way, cheating my engine of the good stuff. Basically, I just decided years ago that after so many miles the engine most likely didn't have the compression any more to necessitate the 91 octane.

 

You took the words out of my mouth. Nothing is to good for my girls!!!

 

93 Octane All Day Everyday

 

Same here, not worth the trouble later if something happens de to bad gas, you might save now but think about the future.

 

You guys really wanna mix it up?!

Use methanol / water injection...yes...on an N/A car. It would come on at a specific level of vacum instead of boost, that's all.

Let the car idle, sit in traffic and get around town on 89oct. Then when you hammer it and see big rpm or drive hard on hot days....let the methanol come online and cool everything off

Jay

 

If I was worried about the price of premium gas compared to regular (about $100/yr) I would have kept my Honda. Gas, Insurance, and repair costs all went up in price with my GS400 but the smile in my heart is worth every penny. Giddy up!

 

I would NEVER put anything less than premium in that gas tank. The buyer should know already that buying a Lexus will cost you when your at the pump too. It's like someone wanting to buy a SUV but yet is naive about the dollars needed to pay at the pump. Premium or even Sunoco's Ultra from time to time.

 

I didn't know that...thanks!
And, I only use highest grade available...it's 93 in my area. Putting in 89 octane would only save me between $2~$3 per tankfull...not worth it IMO.