LifeEnjoyr

iTrader: (1)

Too bad here in Cali, ethanol still makes up about 10% of all gas at almost every gas station I've seen.

Turbinator

Thanks, and just checking, what symptoms would one see for a dirty MAS - I am guessing decreased fuel efficiency is one of the symptoms. Anything else? Would a diagnostic test or a warning light pop up? Anything else to look out for?

And is a dirty MAS a common thing with the K&N filter, or is this more of a rarity?

Turby

T4Fun

few points

the engine is designed for high octane fuel, not low octane.

you should not overfill gas tank as others mentioned here.

finally, overinflating your tire I assume when its cold is a big no no. When you drive it, the pressure goes even much higher on a warm day, like 5-10psi higher.

Turbinator

I recall folks here saying that for certain years, the owner's manual does not call out a requirement for higher octane fuel. I think the cutoff is 2006 and newer asks for higher octane fuel?

Turby

ALAN553

2004 "recommends" 93 in the manual

oardila99

Quote from the reverse side of the back cover page of the 2003 GX Owner's manual:

"Fuel selection:
Select Octane Rating 87 (Research Octane Number 91) or higher. For improve vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number 96) or higher is recommended."

I have filled the tank with strictly premium fuel (93 oct) and wit regular (87 oct) and have noted NO difference at all, hence I continued using regular 87 octane fuel.

I also have an older MB, and in that thing you can absolutely tell the difderence, so I figured that if a real difference existed it would also be easily noticeable.

cssnms

According to the Toyota spec sheet (attached) the pre VVT-i engine and the VVT-i engine both "require" 87 octane or higher (attached). However, certain GX owner's manuals call for or recommend 93 octane or higher.

Given the confusion/debate, I contacted Toyota corporate and they could not explain the reason for the discrepancy not only between certain MY GX's, but also by comparison with what is stated in the 4-Runner V-8 owner's manual despite they all share the exact same engine.

OP, I like Techron fuel system cleaner. I try to add a bottle to a tank every 3 or 4 months.

LifeEnjoyr

iTrader: (1)

91 definitely gives better performance and mileage on my experience. 87 gives the GX less power and I noticed the tank burns a little faster as well.

Momster

Hello,

I have 06 with 37k miles and get 18-19mpg hand calculated 20-21 on the on board computer. I have been using non ethnol mid grade very limited places to purchase from, but happen to have a GranDel down the street from me. I drive a combination of city and highway. I try and stay between 55-65 on the highway, anything over and my mileage it 15-16. I do not baby my rig but do watch for red lights and coast and do not punch it when the light turns green.

ChrisK

iTrader: (1)

Thank you for finally recognizing what was written in the GX owner manuals from 2006 on. The reason - ULEV II.

redrocks

So, have you noticed any difference in mpg using regular?

ChrisK

iTrader: (1)

I never used the regular in it, so I cannot compare. If there is a difference, it probably would be a small one. On the other hand, the engine will run much cleaner using premium.

ALAN553

Don't think premium means more detergent, just higher octane. So don't make cleanliness your reason for choosing an octane. You want clean, stick with top tier gas.

ChrisK

iTrader: (1)

To have clean running engines Lexus changed the recommendation and made the premium fuel the requirement. It has to do with meeting the ULEV II certification requirements.

Here is the difference between LEV and ULEV II

"ULEV II: Ultra-Low-Emission Vehicle, a mid-level Phase II LEV standard. Hydrocarbon and carbon monoxide emissions levels are nearly 50% lower than those of a LEV II-certified vehicle."

ALAN553

Ah, got your point, cleaner at the tailpipe, not necessarily internal engine parts, ie cylinder walls etc...but still not sure octane changes that, the computer compensates for the change of octane?