Klierslc

As the motors age and lose compression, would the pinging occur less often with 87, resulting in the timing remaining advanced???

Alan D

Why would you even risk using 87 when 91-93 is only $4 or $5 more per tank. It's not going to save you much and the reason for using higher octane fuel is due to the higher compression of the engine. Lower octane will pre-detonate and can damage your engine over time. All so you could save $5 a week.

Stupid.

Maybe change your driving style to increase your fuel economy and make sure you do your routine maintenance.

illcelsior

CR is 10.4:1.

That is enough knowledge to put in 91 octane or greater. I personally feed this car 93+.

Around here the difference is about $.15-.20 a gallon.

$.15 x 22.5 gallons = $3.23 more per fillup.
$.20 x 22.5 gallons = $4.50 more per fillup.

Is it really worth it? In the summer months when the intake temps, water temps and under hood temps are higher, it makes no sense to me to try and save a few $ a week.

This is an AGE old debate.. Up there with oil & tires.

19psi

there is aknock sensor which will hear the pinging and pull back timing to save the engine. over time, the ecu will adjust and keep the timing retarded for safety.
so yes, you can use 87. is it good for the car? not at all. lower timing means more stress and heat on the internals. in an emergency 87 is usable but always use 91+ when possible.
if you do use a tank of 87, it could take a few tanks of 93 for the ecu to see that there is no more knock and will gradually give the timing back to the max. amount.

wkinley@gm

Well I started this thread to get peoples opinion about using 87 octane, and the general consensus is that 91 or higher is the minimum we should use in our LS's. I am sure that if the lower octane was satisfactory, their marketing people would tout it.

I appreciate your input; now think it is time to archive this thread.

PK_Celsior

iTrader: (18)

I Use Only 91 Octane Gas. My Dad Try To Put In 87 Last Time And The Car Wouldnt Start. LMao. So We Had To Flush Out All The Gas From The Tank. With My New ECM My Lexus Friend Doesnt Recommend Changing Over Especially Since I Been Sittin My Car On 91 Fo So Long. But Guess What All The Gas Lexus Uses To Fuel Up Those Brand New Cars Is 87 LMAO. We Talk To The Gas Trucker Guy. So If Your Car Is New Why Not LoL. But It Wont Be Running Efficiently As It Will If You Ran The Right Fuel.

mac6694

I had low octane fuel in my car once. Only once, and it ran terribly. a former girlfriend decided it didnt make a difference, or didn't realize what the thing needed, or something. I dunno. But it took a while to get the car running regularly after that.

Personally, I run a quarter-tank of 100 octane race fuel at least once a month just for giggles. funny how much better the car responds to the throttle...

denverdog

there is a great "modern marvels" show on the history channel on gasoline. look for it. it explains octane thoroughly.

illcelsior

Extremely funny since the ECU will only advance the timing so much.. regardless of octane used..

In other words.. Unless you need it; you won't see the gain other than running a modified ECU or after market variant.

I'm running a Blitz ECU and I feed high octane or it will pull the timing due to knock. Otherwise, a little bit here and there will "clean" the tank so to speak.

turbosix

wtf 100 octane. lulz. it was all in your head. higher octane than needed is detrimental to performance.

PureDrifter

iTrader: (10)

u realize in japan 102 is premium right....

thats yet another reason jdm motors and ecus sometimes choke power when they get here and are limited to 97

turbosix

the 100 octane comment was towards the member from arizona.

illcelsior

Just so there is no confusion, we are talking about 102 RON. Not the same method we are using here. (R+M/2)

fwiw, our 100 unleaded is (I believe) 104-106 RON. More than enough to run a JDM tuned ECU. Just damn Expensive. (~$6.50/gallon) Otherwise 94 (when we could still get it) was 97-99 RON as you mentioned above.

(These numbers are from a Sunoco Rep.- My memory may be off a small bit)

Bill Dowd

using 92 or 91 octane is ok here in california I use 89 octane and no problems but I once used 87 and the car and it started pinging and that can hurt and engine over a period of time. Todays gas isn't as good as it used to be so best to run 89 to 93 octane in the lexus in hot weather always use the highest ocatne you can get in cool damp weather 89 octane works fine. each state has a different gas formular try each grade of octane to see what works best.

Lexushead

I've (my wife) been using 89 for so long that when I drive the car it doesn't feel any difference whether 89 or 91.