Premium Fuel or Regular

[Kdbradley85]

I think you've misunderstood the research octane number reference.

Octane is determined by two different methods - Research Octane Number and Motor Octane Number. MON tends to run about 8 points lower than RON. In North America the pump octane number is the average of the two and you'll see "(R + M) / 2" on the labels. So pump octane ends up being 4 points lower than the Research Octane Number.

So when the owners manual says "87 (Research octane number 91) or higher" they're saying choose a pump octane of 87 if it's labeled using (R+M)/2 method, or 91 if labeled using just the RON measure. It's the same fuel.

BTW - my 2017 Tacoma owners manual also says "87 (Research octane number 91) or higher"

Thanks for the explanation. I wasn't sure, but I was referencing another user's post and did a bare minimum google search which seemed to indicate that the "research octane number" meant that the manufacturer tested their motor using that particular fuel. Your explanation makes about as much sense to me lol, but I appreciate the response and I'll just assume you're correct as well! I think this whole thread could be summarized as "just use a top fuel rated at 87 or higher and you'll be fine." As I also stated, I'm most likely not going to spend the additional money on the more premium fuel even if the results are added HP or efficiency. The truck runs perfectly fine on the fuel I've been using.

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[gpburdell]

I think this whole thread could be summarized as "just use a top fuel rated at 87 or higher and you'll be fine." As I also stated, I'm most likely not going to spend the additional money on the more premium fuel even if the results are added HP or efficiency. The truck runs perfectly fine on the fuel I've been using.

Yeah, the octane stuff can be confusing. Especially since there are different measurements and some countries use an average of them and others use just one.

More info - perhaps more clearly conveyed - at Wikipedia

And yes, any of these gasoline threads can be summarized with the advice to use at lest 87 octane or higher, preferably from a TopTier supplier so you know you're getting a better detergent package. That said, I've fueled my 3rd gen at a mix of Sam's Club, QuikTrip, and Costco - with only the last two being TopTier - and so far 100k miles with no issues. I'd say over half the time at Sam's, then most the rest at QT and to a lesser extent Costco.

While it appears higher octane allows the 4th gen motor to produce a little more power/torque, it'll be up to the individual to decide if it is worth the added cost. Around here premium gas is ~20-30% more expensive, so unless there's a significantly noticeable difference (when I get a 4th gen), I expect I'll stick with 87. (I'll note that my Fuelly log for my 3rd gen says I've spent nearly $15k on fuel since I got it in September 2016. and I sure do miss those gas prices too... )

 

[CanyonFisherSummitSeeker]

I think you've misunderstood the research octane number reference.

Octane is determined by two different methods - Research Octane Number and Motor Octane Number. MON tends to run about 8 points lower than RON. In North America the pump octane number is the average of the two and you'll see "(R + M) / 2" on the labels. So pump octane ends up being 4 points lower than the Research Octane Number.

So when the owners manual says "87 (Research octane number 91) or higher" they're saying choose a pump octane of 87 if it's labeled using (R+M)/2 method, or 91 if labeled using just the RON measure. It's the same fuel.

BTW - my 2017 Tacoma owners manual also says "87 (Research octane number 91) or higher"

Yeah I read something on another thread regarding how the torque and HP numbers were achieved and you’re right, I wasn’t using the ROM correctly. Thank you for the explanation

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