85 vs 87

Lower oxygen concentration (air/fuel ratio) has nothing to do with this. This is really an ignition timing issue. Octane is simply how resistant fuel is to detonation under compression. Because lower atmospheric pressure (aka high elevation) effectively raises the octane of all fuels, 85 octane at high altitude will perform similar to 87 octane at sea level. So unless the engine has high compression or forced induction, running cheaper 85 octane will be fine.

 

Were at sea level to 3k'. Only E10 87 to 92

 

toyota says use 87 or higher so i still would use 87 even at high altitude.

 

It's on the YouTube, it has to be real.

 

What about when the gas station doesnt have 87?

 

85 (not to be confused with E85) is effectively 87 at altitude which is why you only see it sold in places at altitude. It will be fine.

 

I noticed that too when I drove thru Utah, I put 89 or whatever available that's >= 87

 

Carb vs Fuel injection, naturally aspirated vs forced induction isn’t really relevant. It’s more about the compression ratio. You can have a high compression naturally aspirated engine that requires a higher octane, same as you can have a lower compression ratio on a forced induction engine and run 85 octane with out an issue. Most forced induction engines tend to run at a higher compression ratio, therefore requiring higher octane. Most, but not all.

 

These new trucks all have exceptional knock control built in, you won't hear any knock, the computer will hear it far before you do and turn down ignition advance, but like everyone else said, 85 is available at an altitude where it is safe to run in place of 87. There will be no knock issues.

 

Even in that video he said it's fine to use 85 if you live up high and stay in the area, have a naturally aspirated engine and don't drive hard. So basically 85 is fine to use in the Tacoma high up.

 

then i would use 89 or 91 or 93

 

Based on my experience with his videos and the fact that he used to be a mechanical engineer, I’m going to trust his opinion over the opinion of randos on an Internet forum.

Did you watch the video? He doesn’t entirely disagree with those promoting the use of 85 octane. I think the title of the video is partly “click bait” and partly a reference to Ford’s published recommendations to not use 85 which he starts the video with.

 

I used it for almost 10 years, the only concern I would have is if you plan on driving to lower elevations on a single tank.

 

My 4 cylinder runs just fine on 85 octane. Running 85 or 86 in the V6 won't hurt anything, but it might make it suffer slightly from mpg and power loss if you use 85 for reasons that involve compression ratios and ignition timing.

 

Watch it...
You might learn something.