92 octane gas

I accidentally filled my truck with premium a month back. It was dead empty too. I noticed nothing other than my wallet being a bit lighter than it would have been. I track fuel economy as well and did not notice any increase either.

 

My 2.7 runs worse on 87 than it does on 85. The first time I put 87 in it, within minutes I immediately noticed it ran ever so slightly rougher. (could have easily been bad gas) No noticeable change in power or fuel economy. Going back to 85 smoothed it back out within minutes. I have yet experience knock even a single time on 85.

I could see the 3.5 taking advantage of higher octane as it has higher compression and dual injection, but I can't see it ever being worth the extra cost. Maybe if tuned.

The only vehicle I ever owned that I could tell the difference between regular and premium was a GS350 that I briefly owned. The only thing I actually noticed was a slight lag in throttle response, probably from the knock sensors kicking in and retarding the timing when I tried using regular.

 

Where do you get 90 octane in Florida? I thought 90 octane was an Alaska thing.

 

Modern engines with onboard computers are capable of adjusting their tune to account for differences in fuel, altitude and other factors. Also, modern engines with higher compression ratios can benefit from higher octane fuel better than those with lower compression engines.

I don't know how the owner's manual is worded on 3rd gens. But many newer vehicles are worded something along the lines of " Use AT LEAST 87 octane" fuel. Leaving the option for higher octane fuel if better performance is desired. Some even specifically recommend going to higher octane fuels when towing but state the truck will still run fine on 87 octane. They also specifically warn against using 86 and 85 octane fuel that is sold at higher elevations that is supposed to work just like 87 octane at lower elevations. The lower 85 octane only works just like 87 octane when used in vehicles more than about 30 years old. They shouldn't even make it anymore. If you live, or travel in those areas skip the 85 octane gas.

I switched over to 93 octane for several months starting last fall up until gas got close to $5/gallon. It made a noticeable difference in my 2014 F150 and my 2020 Explorer. Especially when towing with the truck. The difference in my 07 Tacoma was much less noticeable. But it did hold higher gears better on inclines with less downshifting.

While the Tacoma benefitted much less, I just used premium in all of them for about 9 months. If fuel mileage improved, it wasn't enough to measure. I was paying about 30-50 cents/gallon more and felt the better performance, especially in the other 2 vehicles was worth the expense. But when gas got so expensive I went back to 87 octane. I'd still pay for premium if I were towing, even in my Tacoma.

 

Ok guys, I'm gonna jump on here after all of these threads talking about this. I'm no mechanic, but the one that changes my oil etc has been in business for 28 years. He said to run 92 octane because his brother said to. His brother . . . built engines for Rick Hendrick Motorsports for 23 years. He said lower octane engines run much dirtier and it causes fuel injector issues. He said if you were to take an engine apart that has 25,000 MI on it with 87 octane and take apart another motor that has same mileage with 92 octane you will be amazed. He went into much greater detail than I don't have time to put on here. Take it for what you will.

 

My 280k 3.4 says 87 is fine

 

That depends where, and what fuel you purchase when it comes to the lower grade gasolines. Use a top tier brand 87, and you'll likely never to run into dirty fuel issues. Many of those discount places buy their gasoline cheaper with less detergents added.