What Octane Do You Use In Your 4.0L V6?

Yeah...the owner's manual.

 

then why is everyone stating tthe recommended is 87?

 

Don't do it. It's not worth trying to game the game. If you've got the blower- pay to play. (I ran lower octane in my last truck charged to 11psi and it made a lot of bad sounds and ran like junk)

 

I think people may be confusing Research Octane Rating (RON), Motor Octane Rating (MON) and anti-knock index ([RON + MON]/2) or the average of the RON and MON ratings.

The manual clearly states in section 6-1 (page 467) under fuel specifications that 87 octane (research octane number 91) or higher is recommended.

In the US, the number on the pump (87, 89, 91, 93) is the anti-knock index, not the research octane rating.

 

From wikipedia:

http://en.wikipedia.org/wiki/Octane_rating

A fuel with a higher octane rating can be run at a higher compression ratio without detonating. Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more motive power. Engine power is a function of the fuel, as well as the engine design, and is related to octane rating of the fuel. Power is limited by the maximum amount of fuel-air mixture that can be forced into the combustion chamber. When the throttle is partially open, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than when the throttle is opened fully and the manifold pressure increases to atmospheric pressure, or higher in the case of supercharged or turbocharged engines.

Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.

 

Ok, so clarify this for me, because it's a little beyond my current knowledge level:

What does this mean in terms of fill up? Is 87 anti-knock the same as 91 research octane?

In other words, is it better then to fill the truck with 87 because that's the number on the gas pump that is equivalent to the grade of fuel the engine was spec'd at by Toyota? That's essentially the question I'm asking - what would the grade of fuel Toyota used to spec the engine be called *at the pump*?

That's the confusion here - what exactly is the octane the engine was designed for called at the pump? 87, or 91, or something else? I'm aware that running octane above the level the engine was designed for actually typically lowers power output. The problem I'm having here is determining what f-ing octane the engine was designed for.

 

^^that i have no idea^^i do know that i get absolutely zero knocking in the engine using regular, and assume that the other 50%+ voters use it as well...IDK, i will stick with regular until i can justify the higher cost...or when the suppossed gas drop will happen later this year...so they say

 

Toyota specs 87 anti-knock index fuel for the 1GRFE engine. You are right in your assumption that 91 research octane rating is essentially 87 AKI at the pump.

People who are using 91 or 93 to combat detonation, it may be well worth having your truck checked out by Toyota, modern electronicly controlled engines should NOT KNOCK at all as there are coutermeasures (timing retard, throttle over-ride, etc.) that should control detonation even if lower than required octane fuel is used.

 

I don't know why Toyota even put the RON number in perenthesis on the spec ... it just adds to the confusion.

they should just say, "press the 87 button on the pump"

 

ya, me too, i think i am just gonna stay with 87, maybe 91 or 93 if i feel like blowin an xtra $10 on gas or just to try it out while with like $20 for "testing" purposes, see if power is actually gained, if i cant feel it, its not there!

 

I see, I hadn't heard that. Was is it in a bulletin?

 

Good to know, thanks. Luckily I don't have any knocking issues on 87, even towing a 6000lb boat.

 

well in jersey, if regualar is $2.50, super(91) is usually like $2.90 and sunuco ultra 93 (only place that sells 93 in jersey as far as i know) is like $3.00. ( i am not in jersey till i return from business trip so dont know exacts) but so i ESTIMATED that a 20 gallon tank + $.40 - $.50 extra a gallon is $9 - $10, thats how...i believe that to be pretty accurate. 93 octane is expensive here...

 

jersey has some of the cheapest gas in teh country, for regular i have noticed, as i travel all over the country for work. but we seem to pay more for higher grades of gas. Also thoughm, unlike most of the country, when its sweltering heat or blistering cold, we can stay in the car while habib pumps it for us....GO GO FULL SERVE, wouldn't want to break the law and pump it yourself.....that is unless i am on the motorcycle...then habiib doesn't even get close.