This is the mother of all 2IS gas discussions.

Please post your "should I use only premium or can I use mid-grade or regular gas" questions here if you can't find the answers and opinions you seek from the posts already here.

I've merged several discussion threads on this exact topic together here & will add this to the FAQ.

Keep in mind some of the earlier posts are from just before the 2IS was formally released and specs known (such as compression, etc)

 

Since this will be a V6 engine, do you think it will take regular or premuim gas. Man, gas prices are still way up there & it's killing me.

I know my Lexus V8 baby uses only premuim gas. Since the new IS350 will have over 300 hp do you expect it to take premium?

 

I think they'd recommend at least 91 Octane for the IS350.

 

With such a high compression ratio, I wouldn't be surprised if 91 Octane is required .

 

Anyone knows what the compression ration is gonna be?

 

i have no idea on the compression, but v6 with that much power, i think the compression would be pretty high

and definitely premium gas. i dont' think lexus will make the is350 able to use normal 87 gas

 

i believe the IS350 compression ratio is 11.8:1 and the IS250 will be a whopping 12.0:1. I'm pretty sure premium fuel will be required. In comparison, the Acura RL V6 with 300 HP is a 11.0:1 compression and requires premium fuel.

 

I think Lexus will definitely RECOMMEND 91 or higher octane. However, I do think running 87 will be possible but with degraded perfomance. It would be silly if people get stranded in some remote area just because premium fuel is not available . Just my two cents.

 

Yes, no doubt. As with most cars since the early 90s it will probably have knock sensors to retard timing when using lower octane gas.

 

most luxury brands recommend Premium (91 Octane). As some have said, with both engines using such high compression ratios, premium probably should be used. It's a pet peeve of mine when people don't put the recommended/required fuel in their car. I know a 1998 Audi A4 1.8T owner who puts 87 Octane in his car when 91 is pretty much the needed octane (it's a Turbo, I don't understand his logic!) Off Topic, but I figured I'd share.

 

avalon requires 91, so the IS should aswell

 

could have sworn i saw somewhere that the is250 uses regular gas, not premium. true? what's it say inside your gas tank access flap, new owners?

 

I only wish you were right - inside my is250 gas tank it clearly states that only Preimum Fuel be used.

 

He is right, I have used the middle grade when they are out of premium.

 

Ditto here.