What grade gasoline do you use

[priussoris]

<div class='quotetop'>QUOTE(cc9150 @ Apr 13 2007, 07:48 AM) [snapback]422546[/snapback]</div>

but 93 octane gas costs more, so you're paying more to get more mpg???

Have you calculated the cost per mile for each grade of gas?? mpg doesn't mean anything if you have to pay more for each mile.

if I could give you 100mpg but you'd have to pay $1000 for each tank of gas, you shouldn't do it.
[/b]

We use super unleaded ( 91 ) not Premium Unleaded (93)
here the 91 or super is same price as regular (87) so why not use it gives more for the same $$$

[cc9150]

here the 91 or super is same price as regular (87) so why not use it gives more for the same $$$[/b]

yes, if it's the same price as 87 but gives more miles out of that same amount of money, go for it.

[V8Cobrakid]

This web page (bladder system) has this to say:

OCTANE RATING: At a minimum, the gasoline used should meet the specifications of ASTM D4814 in the United States. For the Prius, use only UNLEADED gasoline with an Octane Rating 87.

NOTE: Do not use premium gasoline. It may cause starting problems with the Prius. There is no gas milage benefit when using premium gas!

NOTE: Starting may occur many times in a single drive cycle unlike conventional vehicles compounding potential "hot soak" issues.

this page explains what a "hot soak" is. section 3.1 All it really says is that a hot soak refers to the evaporative emissions when the engine is off. I have ideas and theories on this but I'll stop with my .02 here.

[jrfaris]

Always use regular unleaded, 87 octane. I can see no mileage difference among brands. With bladder & pump variations you can't rely on brand experience from a few fillups. You would really need to average over all seasons and they all come from the same pipeline anyway. I typically buy by price (GasBuddy maps): Costco, Arco or sometimes Chevron or 76.

[aaf709]

I use 87 and generally get it at Arco (which is owned by BP). At a recommendation from this site, I decided to try Shell (10 cents per gallon more). For a brief time I had hit 73.5mph, but it dropped to my normal. I'll probably try Shell again.

[cc9150]

I can see no mileage difference among brands. With bladder & pump variations you can't rely on brand experience from a few fillups. You would really need to average over all seasons and they all come from the same pipeline anyway. I typically buy by price[/b]

then why does Toyota recommend otherwise with their Top Tier gas recommendation?

That it all starts from the same pipeline doesn't mean it all ends up as equal quality gas at the pump.

If you buy by price, you get what you pay for.

[wdross]

<div class='quotetop'>QUOTE(cc9150 @ Apr 13 2007, 11:52 AM) [snapback]422805[/snapback]</div>

then why does Toyota recommend otherwise with their Top Tier gas recommendation?

That it all starts from the same pipeline doesn't mean it all ends up as equal quality gas at the pump.

If you buy by price, you get what you pay for.
[/b]

All car engines are designed for a specific octane rating to be used. Using a higher grade usually has no affect other than the engine many run a little more efficiently. Using a lower grade octane will run the engine less efficiently and cause maintance problems in the long run. If the engine normally runs mostly for charging the batteries in hybrids, the rated octane for the engine is the best. If you find that you are running the car at higher speeds and requiring the engine to help contribute power to the wheels, using a higher octane may help. The best two examples that I can give are as follows:
My 1986 Celica would get 26.5 mpg with regular (85 octane) but increased to 32 mpg with premium (91 octane, Toyota's suggested octane). Gas was around $2 a gallon with the difference being 10% in cost between regular and premium. This means that premium was the cheaper (!) gas since for a 10% increase in price I got a 20% increase in mileage. Along with this came better acceleration, less gas stops, and less engine maintance due to a smoother and more efficiently running engine.
The second example: a friend of mine had a truck that got 15 mpg on regular. I told him that he needed to check like I did to see if that was the cheapest gas. His mileage increased to 19 mpg on premium! That is an ~30% increase in mileage for a 10% increase in gas cost! More power and less gas stops along with less cost - he uses only premium!
Not every car will show these gains, especially if the engine was designed for regular gas octane (85). And hybrids even make it harder to answer this question. Long term testing on one's own car is the only answer.

<div class='quotetop'>QUOTE(cc9150 @ Apr 13 2007, 11:52 AM) [snapback]422805[/snapback]</div>

then why does Toyota recommend otherwise with their Top Tier gas recommendation?

That it all starts from the same pipeline doesn't mean it all ends up as equal quality gas at the pump.

If you buy by price, you get what you pay for.
[/b]

All car engines are designed for a specific octane rating to be used. Using a higher grade usually has no affect other than the engine many run a little more efficiently. Using a lower grade octane will run the engine less efficiently and cause maintance problems in the long run. If the engine normally runs mostly for charging the batteries in hybrids, the rated octane for the engine is the best. If you find that you are running the car at higher speeds and requiring the engine to help contribute power to the wheels, using a higher octane may help. The best two examples that I can give are as follows:
My 1986 Celica would get 26.5 mpg with regular (85 octane) but increased to 32 mpg with premium (91 octane, Toyota's suggested octane). Gas was around $2 a gallon with the difference being 10% in cost between regular and premium. This means that premium was the cheaper (!) gas since for a 10% increase in price I got a 20% increase in mileage. Along with this came better acceleration, less gas stops, and less engine maintance due to a smoother and more efficiently running engine.
The second example: a friend of mine had a truck that got 15 mpg on regular. I told him that he needed to check like I did to see if that was the cheapest gas. His mileage increased to 19 mpg on premium! That is an ~30% increase in mileage for a 10% increase in gas cost! More power and less gas stops along with less cost - he uses only premium!
Not every car will show these gains, especially if the engine was designed for regular gas octane (85). And hybrids even make it harder to answer this question. Long term testing on one's own car is the only answer.

[alexstarfire]

After years of using Kroger and Walmart brand gas I tried some of the name brands, like Chevron and Shell. What I've found is that the brand name gas gets a littler bit better mpg, but it also gets closer to the computed mpg. Krogers and Walmart gas get like 4+ mpg less than the computer, but the brand name is like 2.5 to 3 mpg less. Shell has given me my best milage so far, by like 5%. After that Shell tank I put in one last tank of Krogers to compare. I'm still on that tank, but unless that calculated mpg is very close to the computed mpg, then I'll be using Shell gas from now on. I think Krogers and such put a little bit of water in their gas, hence the calculated mpg being far below the computed mpg.

[jrfaris]

<div class='quotetop'>QUOTE(cc9150 @ Apr 13 2007, 10:52 AM) [snapback]422805[/snapback]</div>

then why does Toyota recommend otherwise with their Top Tier gas recommendation?

That it all starts from the same pipeline doesn't mean it all ends up as equal quality gas at the pump.

If you buy by price, you get what you pay for.
[/b]

Toyota probably get's some benefit from the major producers for including the Top Tier. Or was added by their lawyers, not their engineers (like the I agree button).

You are right that there are some brand differences but the basic gas is the same. The difference is the additives put in, usually cleaners, etc. These may or may not be good for your engine long term. They are often just a marketing ploy.

Anyone who relies on price as a measure of quality is misguided. This would imply that purchasing gas at the most expensive Chevron station by the freeway would give you a better product than the cheaper downtown Chevron.

[jrfaris]

<div class='quotetop'>QUOTE(wdross @ Apr 13 2007, 11:54 AM) [snapback]422862[/snapback]</div>

Long term testing on one's own car is the only answer.
[/b]

That is correct. There is no way a mileage benefit (or penalty) can be determine from a few tanks of gas. Unless you run a single brand from a specific area for many fillups, there is no way to compare. In fact, if there were a benefit, it would likely be seasonal and one brand may be better with their summer formulation where as another might be better during the winter months. Just doesn't seem like a useful exercise to me.