What do you run?

How many miles on your truck?
You should get better MPG after it breaks in.

 

This is incorrect. All else being equal, a higher octane gasoline has just as many BTU's as a lower octane gasoline. Higher octane fuels burn slower, creating a more progressive flame front, which reduces detonation. There would no temperature difference in either sample.

Also, while it's true that you may be wasting money by burning a higher octane gas in a engine rated for lower octane, it's also possible in today's engines you may not be wasting money. Due to the increase in automated control of fuel delivery and combustion it may be that an engine can effectively burn several grades of gas, and possibly give degrees of better performance/mileage with higher octane fuels. Only testing using a reasonably good scientific method would we be able to tell for sure. Heuristics using anecdotal evidence (which is what we typically do on TW) can provide fairly accurate results if the sample size is large enough and the variables are minimized. If neither method is used appropriately we're just shooting the breeze comparing personal experience. Which is fine as long as we want to be entertained comparing notes and not taking individual results as gospel.

</nerd>

 

http://www.toptiergas.com/

Toyota and others got together and established a higher standard for detergent additives. They suggest it is about double the amount required by EPA. Most major gas brands are on board now. Valero is the most recent major addition.

No mention of grocery chains except Costco. No Citgo, Sunoco, Racetrac, 7-11, Pilot, Amoco, etc. You can look at the retailer list.

 

Ignoring a possible performance gain. Premium is >20% higher cost than regular. In a properly running vehicle there is no way you will get >20% better fuel economy. So, you would be wasting money wrt mpg.

 

There are now 2 threads on this I see. So I will link what I typed in the other if it helps anyone.

https://www.tacomaworld.com/threads...d-where-do-you-pump-your-gas-at.400667/page-3

 

this

higher octane usually burns hotter too. can seriously ruin some stuff if the engine isn't designed for it.
I have heard that if you run 87 usually and then every 3rd tank fill up with 91. It helps burn off carbon build up. Could be a myth though.

But regardless different octane usually doesn't effect MPG, nothing significant at least.

Little FYI for all those that want to run 94 Octane, friend of mine went to university for chemical engineering and one of his professors for his PhD actually wrote his thesis on 94 Octane. After doing test etc found that 94 octane is just added ethanol and no better than 91 for majority of cars (this was done comparing Shell 91octane to Petro Canada 94 Octane) Besides this I have heard numerous time the same thing. When it comes to 94 vs 91 at times the 91 is actually better. Unless your engine is designed to work on high ethanol fuels (flexfuel GM/Fords?) it may just clog up your injectors and cause problems.

 

the other vehicle I was looking into getting instead of a tacoma was an Audi S4 (completely different class I know) but the MPG was actually better from the V6 supercharged audi vs the tacoma by I think 3-5MPG...but when you account for the higher octane required fuel its actually more money to fuel up.

87 is 1.03 a Litre here, 91 is usually around 1.25-1.30/L

 

"Unless your engine is designed to work on high ethanol fuels (flexfuel GM/Fords?) it may just clog up your injectors and cause problems."

This new Taco has a injector clean mode specifically for this reason. So it shouldn't be a factor.

"Drivers may hear the self-cleaning taking place during an idle, and the process could last from 10 seconds to as long as 10 minutes, depending on driving patterns and the amount of build-up on the injectors."

 

The worst thing for any gasoline engine is ethanol, find stations that sell actual gas, not the politically-motivated and privately funded crap they are forcing down our tanks.
http://pure-gas.org/

 

As it should be. It's forced induction motor hence why you must run premium. I just sold my Audi for the Taco. As well the car is lighter and more aerodynamically tuned then a lifted truck obviously.

 

I always use 91. Its usually chevron although sometimes I use Conoco or Shell. I have used some off brand stuff once and that was because I was in the middle of nowhere and had no options. I usually get about 20MPG.

 

Very true while we're at $2.00 for regular with a $0.30 addition for premium (which is about what I'm seeing locally). In this case, if you're getting 20 mpg, you'd need to get 23 mpg with premium to break even.

But if gas should rise to $4.00 (not likely in the near future) and there's the same $0.30 addition for premium, now were only talking 7.5%. At that price range if you're getting 20 mpg on regular you'd need to get 21.5 to break even.

What I'm trying to say is if people really do get a noticeable increase in performance or mileage the price/benefit ratio needs to be accurately calculated to figure out whether or not your wasting money.

Higher octane gas does not burn hotter. If you have carbon on your valves or in the combustion chamber detonation can occur due to the residual heat stored in the carbon prematurely igniting the gasoline. Using a higher octane will minimize that effect, but only as long as you're using that octane, or until the carbon is reduced or removed.

Ethanol is known to raise octane levels, however it's about half the BTU value of gasoline. So, theoretically with a 10% ethanol blend you'll get 5% less mileage. Not sure what the details of your buddy's professor's findings were, but gasoline can reach much higher octane than 91 without ethanol, but not without additives. Check avgas and racing fuels as examples. However, he may be talking about either pure gasoline, or perhaps normal pump gas in which case ethanol is a cheap way to reach higher octane levels.

 

Methanol is about half; ethanol is about a third less than gasoline. So, expect ~3.3% less mpg for E10.

 

+1.
OP gets -1 for vague thread title.

 

Yep as others said. Ethanol kills mileage and most gas stations have it. Some of the Quick Trips in my area actually sell Ethanol Free fuel. It costs about the same as premium. I run it in my motorcycles.

I would bet the EPA and Toyota does their tests with Ethanol free fuel.

 

You win! How much did you bet?