Gas

Damn I don't know what kind of math I was doing... edited the post thanks...

91 is a cleaner fuel - in top Teir fuels, like shell and cheveron, their 91 fuels have more detergents in them than 87, and there are less "deposits" left in the injectors and throttle body.

 

I was scared I was the only one with these differences.

Coot

 

I found out this weekend that if I put pure gas in it increased my total tank mileage from 371 w 87 octane to 380 w/pure gas....

 

I'm curious as to your thoughts regarding what you wrote above and the following statement from the TopTier site: (emphasis theirs)

Are you suggesting that the detergent package in 87 octane TopTier licensed brands isn't good enough? How many miles would you need to drive before this difference actually became meaningful? As in impacted performance in a noticeable way and/or necessitated repairs that wouldn't have been necessary with the 91 octane.

With that assessment we can figure the cost of the higher octane fuel against the cost of repairs and determine if it's worthwhile to bother with.

Thanks.

 

The cost of repairs is unlikely to be a factor as on port injected vehicles with fuel delivery pre intake valve, deposits are unlikely to result in any sort of repair needs, and with most direct injected engines not using a port injection add on (like our engines) are going to get shitty regardless of the fuel used.

The added benefit as I envision it to be, is long term assurances that the valves are not having power/efficiency loss as a result of poor flow due to deposits. Though it's unclear in my mind whether or not that's truly a justification for premium's additional cost. I see the octane as the primary factor.

I'm curious to see what impact an Atkinson cycle engine has on valve cleanliness as you're introducing back flow through the intake valve.

 

I never understood this. All it is really going to do is retard timing to prevent knock or vice versa, and I'm pretty sure it does that on the fly as it senses it. I'm not sure what it would be "learning" that takes several tanks.

 

From said website, it looks like those requirements are a minimum for the base fuel. Wouldn't this mean that this is a minimum requirement to use the phrase "top tier" at their pump... using shell as an example, their nitro plus 91 has more detergent additives than any other brand.

Refer to my original post where I said this was just my opinion... everyone is entitled to one.

No performance gains were noticed other than less pre-detonation pinging...

Also in reference to my mechanic... no one has to listen to him. I choose to because his shop has been in the family for 60 years, and he is a encyclopedia when it comes to automobiles. IMHO, real life experience is gold.

Take from it what you will, or none at all.

 

ethanol free is best answer in my opinion. What you spend extra you get better mpg that equals cost but runs better.

 

General consensus is: You are just wasting your money with 91.

 

So higher octane = cleaner fuel systems ? OKAY

 

Feel free to read back just a few posts. Premium fuel will contain more additives in addition to higher octane for some fuel suppliers.

 

Right, and my question is that if the base level is sufficient to earn the TopTier designation is "good", what then is the real world benefit of going above and beyond?

You mention less deposits. I don't dispute that may well be true. However it isn't clear how that translates into a quantitative benefit. It seems you equate "less deposits" with some real world benefit you will realize down the road, and that is what I'm seeking to learn.

Now if that base level required for TopTier designation isn't good enough to dramatically reduce issues caused by deposits etc. then that is something we should know about as well.

I'd rather deal with facts on stuff like this, thus my questions since you seem to be relatively educated on the topic.

 

No, not necessarily.

Octane has nothing to do with keeping your fuel system clean. It only affects the fuel's tendency towards detonation.

Some (many) brands add more cleaning additives to their higher octane fuels, so choosing the higher octane options may provide more cleaning agents -- but it's not due to the octane.

The real question is where in that spectrum of additives to we get beyond what's needed. Cleaning your kitchen counters with a half cup of bleach in a gallon of water will sanitize things quite well. So what if we double the "sanitizing agent" in the bucket by using a cup of bleach? Won't make the counters any cleaner, and will just empty your wallet faster.

I'd like to know what amount is needed to do the job. Is Top Tier regular enough? Or is more necessary? I don't know, so I ask.

 

If the general consensus were always right would you vote for Hilary?

 

If your gas isn't good enough to prevent knock under the load conditions your truck is being submitted to, the computer will reduce timing to eliminate knock and protect the engine. The truck should run properly with 87 octane, if it doesn't the timing will automatically be reduced. Reducing the timing will reduce power and economy. If you have ECO in your dash display you can see how close your economy is tank for tank.

Swapping up to a higher grade of gas would show better fuel economy only if it allows the truck to run properly with more advance as programmed in the computer and reduce the number of times the timing is restricted do to spark knock. I would expect that very few trucks would have an issue with fuel grade unless you are climbing hills regularly with a full load in a hot climate with blended gas. Something out of the norm from what the truck was designed for.

Without a battery of tests with a consistent route you probably won't see much change. The one caveat to this would be trucks running larger tires without the gear change. You could easily tip the balance in favor of spark knock. There is no way to tell what the computer is actually doing but if there is knock it will reduce the timing. How far it will retard or when to go back to advance who knows, it's in the math tables. When comparing grades of gas the octane grade means nothing but slower burning gas. Putting it in an engine that isn't tuned for it gets you nothing but more expense. If it keeps the engine from reducing timing you gain something. If you engine never knocks then you gain nothing. Unfortunately the only tuning gauge available to most people is the miles per gallon gauge. It takes several tanks to prove the results.

 

Before any lift I started experiencing pinging for no obvious reason. I thought it was just warmer weather and bumped up to 91. I liked the change in feel of the engine after a few weeks and kept with it. Eventually the pinging returned, cold, hot, didn't matter. Under a load at less-than-ideal RPM I'd hear the bees wake up under the hood.

Low and behold: TSB ECM reflash later and it's solved. I keep running the 91 as I like how it feels. I don't know what it did for my fuel mileage if anything. I don't care. A full tank is ~21gal and if you're filling up from a 1/4 tank remaining (like you should) you're probably putting in 13-15 gallons. 91 octane is usually $0.20 more per gallon than 87.

If you're losing sleep over $2 in fuel, I think you should have let the dealer talk you into that prius rather than your "big bad truck" bruh.

All of this is qualified by the fact I have a 1GR-FE and not the 3.5L. The point of the above is : this poster is essentially wrong as the engine doesn't simply dial out pinging.