theking

With gas prices going higher and higher, has anyone tried running 87 octane "Regular"' gas in their 2006 GS300, non-AWD? I've done some seaching, but couldn't seem to find any definitive answer one way or another, other than it's "supposed to" only use "Premium" gas, 91 octane. I too just bought a new 2006 GS300 non-AWD. In my 2002 ES300 which I traded in, it also said to use Premium. I did find that I could run it just fine on Regular, and never ever had any problems.

So can I run "Regular" on the new one? What's the RIGHT answer? Is it SAFE to do so as I did on my 2002 ES300? I live in Torrance, CA.

Any advice is greatfully appreciated.

Thanks,

Alan

Little

Usually with the newer cars, they all have knock sensors that when a knock, or small detonation occurs due to a gas of insufficient octane such as 89 and below when the recommended is 91 due to higher compression, the cars computer will retard the vehicles timing and thus reducing power but saving the engine from a piston failure. So, i guess you could get away with a lower octane, but i wouldnt run under 89. I don't know how fast the computer retards the timing, and if it does allow some detonation.

LexFather

The car will run with no issues but
1. Performace will suffer
2. Engine knocking will occur
3. You will get worse gas milege

The reason premium is the gas to use for most luxury cars is it keeps the engine running efficently and at its maximum. If you use regular, your paying for less gas but you will lose gas mileage anyway. So its a moot point.

Guys, take it easy with the slapping of the thread.

rominl

iTrader: (4)

using regular compared to premium, over a yr you probably save about 200 bucks....

Gojirra99

Yes, & that's if one drives as much as you do

Mr Johnson

So avoid the Starbucks and use the $$ for the premium.

It should be safe but you will make your car

DaveJ

In addition to what others have said, why pinch pennies for gas on a $50,000 car? Even though 91 octane costs more, it's worth it for reasons of performance, gas mileage, and peace of mind that you're not damaging the engine in any way. The engine's designed to run best on 91 octane, and not anything lower.

LEXUS FAN!

I heard it's okay to go for a lower octane, but it is not good to go for a higher octane.

theking

Dave,

I do agree with you. The primary reason I was asking was only because on my previous 2002 ES300 I saw nor felt any real discernable differences in performance in using 87 octane. But then on the other hand, I only had 13,000 miles on it.

So maybe one could say that it wasn't really broken in yet.

Alan

bigzip

I had a '99 ES300 with 92k miles. I used 87 octane gas in it since the day I bought it new. I never had any problems with it and it ran fine. However, I'm on my third tank in my '06 GS300 AWD. I used 87 the last time and it does feel a little sluggish. I will be using 91 octane from now on.

Sandman

High compression in engines like the GS300 can cause the gasoline in the cylinder to detonate prior to the spark igniting. This is called pre-ignition - or "pinging" due to the sound that the engine makes when this happens. Higher Octane gasoline (91 - 93) is designed to be more resistant to igniting from high pressure and usually takes the spark of a spark plug to get it to explode. Which is good because it only explodes when you want it to. Lower Octane gas is more prone to explode from the heat and pressure of a compression stroke in the engine - when the piston is moving upward and the fuel air mixture is being compressed.

When an engine is operating properly the fuel/air mixture combusts when the spark plug fires and the piston is near top-dead-center of its cycle. Everything is functioning according to very precise timing. Some pistons are moving up and some are moving down and they are all working to move the crank shaft in the same direction. They are in harmony with each other.

When pre-ignition occurs the piston is moving upward and has not completed its stroke. However, the explosion from the pre-ignition is now trying to force down the piston while the other pistons are trying to force up the piston (via the crank shaft) in order to get it to complete its stroke. The pre-ignition is actually creating a reversing force or a counter rotation force. When pre-ignition happens the pistons of the engine are fighting each other! The lower the octane, the earlier in the cycle this pre-ignition can occur and increase the counter rotation force. This reduces power, reduces fuel economy and puts a lot of stress on the engine.

The knock-sensors will reduce pre-ignition by retarding the timing, but it may not stop it pre-ignition entirely. Pre-ignition will certainly reduce performance - but if the knock-sensors kick in you may not even know that you are driving around with retarded timing all of the time and wondering why your car is sluggish. With such a high compression engine I'd be cautious about running below 91 Octane. I would want to ask a Lexus Tech about how well 89 octane was designed to work and get more info.

rominl

iTrader: (4)

even better, i don't drink coffee. maybe that's why i never felt the issue with gas

nysupraman

when we bought the RX, the dealer told us for some reason, that since the engine is a VVTi, lower octanes are preferred, i never understood it, but im no mechanic. the jeep runs fine, and now on the GS we do same, use lower octane, on my non VVTi SC i use premium 93. does it make a difference with VVTi?

rominl

iTrader: (4)

ok, slowly walk away from that salesman, and NEVER ever return to him.....

read your own manual, see in anywhere does it say use regular over premium. on the other hand, see if it says premium is the recommended fuel for the car

theking

I second that advice. When we bought our 2002 ES300, the manual DID say Premium 93 was recommended, but our salesman did say that you could run 87 if we so chose, others had, and it would still perform well. I did, and it did perform well. Never had a day's worth of trouble with it in that respect.

When we traded it in for our 2006 GS300, the same salesman said, DO NOT run anything but Premium 93 in it. So it seems that the consensus is run Premium 93 octane ONLY, and that seems reasonable. But I did have to ask.

Alan