3.5 V6 Atkinson Cycle engine and the gas grade parade extravaganza...

That was a good title wasn't it? Anyways... I have a 2017 TRD Sport 4x4 with about 1500 miles on it... Now, the manual says it drinks 87... And I read somewhere (the manual itself? I don't remember) that higher grade will in fact increase fuel efficiency... So, because I am in love with my baby blue, I decided that she deserved only the best and started fueling it up only with 93, what the hell! I went through 2 tanks like that and noticed some vibrations when revving up which I read all around the interwebs... no complaints it's a truck I did not expect a Rolls Royce.

Today however I decided, based on some reads (I know I read too much), to fill up with 89... Mind I was on EMPTY... like 15 miles range left... And I noticed right away that the ride was A LOT smoother... Now, this might be just me and my mental disorders but could it depend on the gas grade?

I am abso-effing-lutely not an engineer but from what I understand the higher the octanes the higher the compression needs to be since the gas is less volatile... The Atkinson cycle however has a lower compression ratio... So if 2 plus 2... The lower the grade the better the cycle should run? I don't know... can anyone competent weigh in please?

I will keep experimenting... Will run the whole tank down with the 89 and try the 87... and see the difference.

 

Just use 87 octane, but stick with top-tier brand gas stations. Buying higher octane fuel is just voluntarily lining oil companies' pockets.

 

I've used 93 and 89 top tier shell so far, getting about 17-22mpg and feels fine. I'm gonna try 87 octane ethanol free next and see how it performs.

 

Lots of variables, but this model and this engine are designed for 87 octane only, the previous engine supported all grades officially.

I've noticed that the truck likes 89 and 91 personally, but I don't run it unless I'm doing a highway trip.

 

I don't think I noticed any vibration with the first tank filled by the dealer... Which I am 100% sure was not 93... yeah right... lol

I know that higher grades are bull butter... But I just couldn't put 87 in my brand shining new Taco... I guess she wants what she wants... and she wants McDonanld's instead of Ruth Chris... Well whatever

 

just run 87. save your money lol

Sometimes putting a higher octane can actually damage engines instead of improve them.
The engine is designed to run on the compression rating of 87. Put a higher compression rating and you can cause problems.

 

Now you are making me uneasy...

 

This. Higher octane is really only useful in engines that are designed for it with higher compression ratios. Sometimes, a computer controlled engine might advance the spark timing since the gas burns slower and you might feel a change in response, but it overall, it won't necessarily make the engine run better. You really have to do some serious testing to determine if there is any improvement.

Use what the manual says, use top tier gas and quit thinking about it. It ain't McDonalds or Ruth's Chris, it's round peg, round hole; wrench for a bolt, or hammer for a nail.

 

Just FY'allI I found this in the manual...

You must only use unleaded gasoline.
Select octane rating 87 (Research Octane Number 91) or higher.
Use of unleaded gasoline with an octane rating lower than 87
may result in engine knocking. Persistent knocking can lead to
engine damage.​

 

There is nothing in the manual about the positive effects of running any octane fuel higher than 87.

Your truck is not running smoother because of the fuel

 

Don't be uneasy. There is no such thing as a "compression rating." There is Octane Rating, and Compression Ratio, but those are two separate (but related) things.

Putting 93 octane into your tank is not going to damage anything. It's just not. Putting something like 102 race gas in, yeah, the gas is going to burn cold and slow and run like shit, and probably foul up some stuff.

I won't turn this into a never-ending science lesson on gas grades and ECU programming, but suffice it to say that on a non-turbo car that's tuned for use in a truck and designed to run on 87, it's just wasted money and not much else. Since you noticed you feel the car runs better with a lower grade, go with what your truck likes.

 

That means 87 octane is the way to go, and ignore the RON 91 octane rating. In layman's term, 87 octane rating equals RON 91, but ignore the RON number to avoid confusion.

Also, if you can find pure gasoline (meaning no ethanol added like E10), then that'd give you slightly better mileage. Unfortunately, not many places carry non-E10 gasoline.

 

Lots of uneducated people throwing around assumptions In here.

The manual actually states use 87 octane OR HIGHER. aka running premium fuel will not harm your truck, at all, in any way. If it did, it would specifically say "use only 87 octane, nothing higher" or something along those lines.

 

You are the bomb diggity...

 

please read how I answered the OPs question correctly

 

For the record, I only said using anything higher than 87 octane is just lining oil companies' pockets. I know you're probably not talking about me, but I just want to emphasize my innocence

 

ok 87 sounds great its corn fuel... and you should use a shell, exxon etc but how do you know what that gas really is nope you dont.. I will save some cash and go back to 89! i know its all ethereal corn mash bullshit and i will always use a fuel treatment

 

Tsk... I knew all that... I'm edumicated...

 

I wasn't really pointing any fingers to be honest, just trying to spread some correct info is all.

I basically run premium exclusively and here is why - first off, my last 5 vehicles have been turbocharged Audi's that required it, so I am used to is - secondly, I put about 5,000 miles on per year, at 20mpg that is 250 gallons of gas through my truck per year. Premium is about .20 cents more expensive which means I am throwing away about $50 per year, aka $4 per month. And that is assuming there is zero added benefit. I honestly believe premium fuels with less ethanol are worth the extra $4 per month. I look at it as costing me one Starbucks coffee (I don't drink coffee so it offsets itself).

 

That's why I'm gonna try the ethanol free. It's not top tier but there's no top tier ethanol free gas to get in my area.