Does premium gas make a difference???

I tried it once and found it resulted in lower mileage.

This question has been the subject of several earlier threads, so you may want to run a search to see other views. Look across all of PriusChat, not just in the GenIII forum, because the issue has been around for a few years.

 

Premium gas depletes my wallet faster than regular gas. On the other hand, gas mileage is about the same.

Keith

 

arrggggh! dont use it. well, i should state that i wont use it. these are modern non caruretted cars with computers. prius is not designed for high test. it will not improve performance. in the old days of points and all that junk it was a different story. go by the manufacturers recommedations. all the other stuff is old wives tales.oooooops i meant mature spouses illusions.

 

In my GII I found that the premium gas lowered my mpg. I did some research and my understanding is that many areas increase the octane rating by adding ethanol (or other chemicals) with has lower BTUs of energy and hurts your mileage. As i understand it octane is a measure of a fuels volatility (the higher the number, the less volatile) . Want to increase your octane? just add some water to your tank (I wouldn't reccomend it), you would increase the octane rating but won't help mileage. Unless it causes your car not to start in which case your mileage would be fantastic since you won't be buring any fuel while pushing it to the dealer.

G

 

Here's an easy to digest discussion on the subject:
Car Talk | Premium versus Regular

 

I don't use premium, not as a rule, but after a long time on regular -- several months -- I have seen a slight improvement in mpg, but for that fill-up only. Conclusion: Higher octane is a negative, not a benefit but the solvents in premium are useful for cleaning an ICE after a period. In other words, premium isn't to be used as a fuel, just a very occasional tonic.

 

WHOA! That site gives some VERY bad advice. While it's true that an average vehicle (such as the Prius) that is tuned from the factory for regular fuel will see no benefits from using premium, a vehicle that is specifically tuned for premium could suffer from detonation and severe engine damage if regular fuel is used.

Octane's purpose is simply to retard ignition and prevent detonation. The higher the octane value of your fuel, the slower it will ignite. If a car (such as my weekend driver) is equipped with forced induction or an extremely high compression ratio and requires a high octane or premium fuel, then a high octane fuel should always be used. Detonation can destroy an engine very quickly.

As for the prius, stick to regular. You'll get better fuel mileage and spend less money.

(This is coming from someone who has worked in the automotive field professionally and recreationally for many years.)

 

Some cars that "need" premium but can work all the way down to regular, usually get better mileage with premium than with regular.
Their computers can handle the lower gas grade and adjust accordingly. In other previous life we discussed this to death and the consensus among the owners of a model that needed premium was that the lower mileage with regular was compensated almost by 80/90% with the savings in gas pric:mod:es, while enjoying lower performance and power. All in all: not recommended.

It has never been a good idea to waste money on premium if the Prius does not require it.
Yes, many gasolines put more detergents in their premium types, and perhaps it is a good thing to add a tank of premium every 20 or 20 tanks, but if all you want is more detergents just add a bottle of Techron to your regular tank of regular and at least you would be 100% sure of the detergents/additives you are adding (you'll never know when buying premium). Additionally, wheh buying premium make sure you buy it at a gas station that sells a lot of premium as gas, like everything else in life also gets old! and therefore will lose octanes, detergents, etc.
I am sure in the present recession the sales of premium have slowed down considerably and therefore, the chances of buying "stale" premium have increased.

 

As a long time racer I agree with the above. Some cars need it while others don't. In some situations a car that doesn't usually need high octane fuel can benefit from it but this is due to the vehicle having very high miles which usually results in heavy carbon deposits on the pistons and/or valves. This condition can raise compression and cause hotspots which lead to pre-ignition but these are rare cases so all in all..... The Prius doesn't need nor will it benefit from higher octane fuel.

 

My old 86 Honda shadow ran horribly and had suffered diminished MPG with higher octanes. It preferred the swill. Now, my Caddy adores 93!

 

Toyota recommends an octane rating of 88 or higher. How much of a difference that makes regarding fuel efficiency...I don't know.

 

It's actually 87 octane. The 88 was a typo.

 

You mean a typo in the owner's manual, since that's what I'm referencing?

 

Yeah, it was a typo.

Here you go:

http://priuschat.com/forums/gen-iii-2010-prius-main-forum/61874-88-octane-2010-prius-whats-up.html