87 vs. 89 vs. 91 Octain fuel. My findings....

So not only does the truck run better on 91 it also cost less. I suspect this would be true on many cars and trucks. However, most people have bought the standard line (mainly from the media) that 91 is a waist of money. Also, most people don’t have the minimal math skills to figure it out for themselves.

 

But - how many people can say they actually improved their gas mileage and by what extent?

It's a similar situation with buying aftermarket air filters or even exhaust - that you'll increase mpg. It doesn't always work for everyone. You have to experiment for yourself.....

 

You have to have a certain mechanical sensitivity to notice the difference in performance between 87 and 91. So all the people that spend their car time listening to their stereo on volume 11, or blabbing on their cell phone, or texting nonsense to their friends, will not notice. On cost, even if it was a wash it is still worth filling up with 91 because of this performance advantage. I did my own experiment and 91 is worth an extra 2mpg - more than enough to offset the extra cost at fill-up.

 

The 4.7L is a V8....isn't it? Never heard of Dodge making a 4.7L V6.

So - you're comparing the gas mileage of a V6 to a V8.

But yeah, I agree with some...your gas mileage sounds low. What kind of terrain is the Loop you speak of? I haven't got anything less than 18mpg in my truck since I got it.

 

Jan-you drive a VETTE!! Hence the skepticism. What is that baby, like 345HP??
I jumped in here at this point cause, aside from the mileage improvements meticulously studied by Chris, I myself get only 91 octain because with it my engine runs at optimal timing advance-hence max power. With lesser octain those knock sensors tell the ECU to retard the timing to eliminate ping=power loss. I swear to you here Jan-I have not heard ONE ping ever utter from ths motor its whole life! Thats why I like it.
You are obviously content with your truck on 87-those sensors do a great job...AND your V6 has more than adequate power so the loos over octain is moot.
But like I said in another thread on this, with lower octain, your knock sensors retard timing=power loss-and with that power loss comes a natural tendency to increase the throttle to achieve a value of power=slight mileage loss overall. THAT is where the mileage thing is rooted

 

I'm not againest running 91....I might try it sometime. But the small benefits chris is seeing - might not pertain to everyone based on driving habits, driving conditions, & many other variances.

Chris was comparing his v6 gas mileage to a V8.... and a Dodge V8 at that. His gas mileage does seem a bit low.

As for the vette - it gets better gas mileage than anything else in the family. It requires 93 octane and we got 32mpg going to Virginia in it. The 6 speed is geared so low that it cruises along at 70mph at 1500rpms. Why couldn't toyota do that with a v6?

 

I wish it wasn't true but I have just last night got 15.98 mpg. Seems my mileage is dropping.

 

Wow talk aout having the best of everything in a vehicle-AND your vintage of Vette is the best of all the later styles including the new ones IMO
As far as why Toyota couldn't do a 6-speed-I'm thinking it's because the Vete has way ample low end torque and power-to-weight ratio that the truck dont

 

Well, there's your problem right there!!

Slow 'r down and run the tests again.

 

I think this whole discussion is a little over your head.

 

The slower burn of 91 just might take away power. I have a V-Rod & my neighbor has a V-Max. When we go out riding he must find a Citco with 104 or 110, I just shake my head and smile.

 

i agree 100%! i always drive with the radio turned down to hear my engine and make sure i have no leaks. the pinging is also noticeable when using lower grade octane

 

When I purchased my Tacoma the dealer said 87 octane. I use 89, the compression ratio 10.0:1 so I thought 87 was low. If the temp is 105 & your towing, 87 octane must sounds like detonation city. Does the computer retard the timing if it starts knocking? What octane does Toyota recommend? Also is it a RON or MON rating?

 

87 is what toyota recommends

 

That seems low for 10:1 compression, I had read on a thread the 4.0 has a Hemi type head. That might be why we can get away using 87.