Premium fuel?

I can't get 87 at Costco here. Either 85 or 91.

 

85 @ 5000' = 87 @ sea level.

 

We are mostly below 5000'.

 

CO mean elevation is 6800' ASL, the highest of the 50 states. Lowest point is 3315'. Higher altitude = lower air density, which mean less heat generated during combustion and a lower likelihood of detonation or pinging. Most vehicles that require 87 octane at lower elevations will see no difference burning 85 octane fuel at the higher elevations encountered in CO.

 

Yes I know, just mostly below 5000 where I drive. Probably close enough that it wouldn't matter though.

 

Manual says 87 octane-rated gas.

 

If it's not pinging on 85, then it's fine. You can try running through a few tanks of mid-grade and see if it makes a difference for you, but my guess is that it won't.

 

$1 per tank? Are you filling up when your tank is half empty? You are just padding the pockets of the oil refiners and gasoline wholesalers.

 

Correct.
That would be pouring $$ to the drain.

 

There will be naysayers about my comment but I am going to say it anyway.

My truck does indeed get better fuel mileage on 91-93 octane when I am towing or heavily loaded than it does on 87 octane. So I use 91-93 for those activities and 87 for daily driving.

 

Technically, it says "87 or higher"

 

Doing my own testing, I have found that my truck doesn't have as bad of "engine knocking sound" when accelerating up hill with 91 vs 87.

 

How much better? I seriously doubt that you break even. Around here it would take at least a 25% improvement in MPGs. So lets say I get 12 towing my boat. 12 x 1.25 = 15. No way I am getting 15 or even close with just a change in gas type.

 

I've tried 93 and 87. Not really any difference in mileage for me.

 

Normally, I fill up when I have around 1/4 or a little over left. Rarely do I wait for my light to go on.

 

Doesn't the manual say something about the rated MPG testing was done with 91? I'm sure I read that somewhere.

 

Correct, that's because it doesn't hurt to use higher octane gasoline.

 

True. Good catch. As a scientific technical writer, I am embarrassed. On the other hand, I am not getting paid to post on Tacoma World; so I can be sloppy with my writing!

 

Is it okay to alternate between 85 and 91? or to even mix the two?

 

The factory manual says 87 octane-rated gas or higher. 85 is not acceptable.