Regular, Plus or Prem?

I think Toyota spends millions of r&d dollars configuring the engine (as well as tire pressures) to give the optimum performance return for the least cost. If you want to burn plus or premium, go for it. But the only thing that will change is your wallet. Just my $.02

 

+1

 

The Prius engine is designed for 87 octane fuel. Performance engines like what was likely in your Acura that take premium only (usually 91 Octane) have engines that have higher compression and also sometimes run at hotter temps. A quick summary the higher compression and heat makes the fuel detonate easier or quicker occassionally causing a misfire or knock. Higher octane fuel will not detonate as quickly which is why the high performance engine uses it.
In other words don't waste your money
If you want to read more on the subject try these links
[ame=http://en.wikipedia.org/wiki/Octane_rating]Octane rating - Wikipedia, the free encyclopedia[/ame]

[ame=http://en.wikipedia.org/wiki/Compression_ratio]Compression ratio - Wikipedia, the free encyclopedia[/ame]

 

The Prius actually has a 13:1 compression ratio, which is quite high, but because of the Atkinson, or Miller, cycle, the need for premium is negated. In fact, I've seen a number of articles that suggest regular will actually perform and maintain the car best. Any experts on fuel/Atkinson that can confirm what I've read?

 

The 13:1 figure is really an expansion ratio. The compression ratio is considerably less, and variable. The Atkinson cycle allows the two to be different.

 

Premium gas is still something on my list of things to try.

In Canada, Shell Premium has no ethenol, so there might be an advantage there.

It also bothers me that Toyota originally specified 88 octane in their manual instead of 87. I know it's said to be a typo, but company politics is a powerful thing and perhaps there's more to it than what's being publicly admitted...

Anyway, since it won't hurt anything, the easiest way to tell is to try it for a few tank-fulls and see if it makes any difference in the way the car runs.

 

Giving the oil companies more money than necessary is not the reason you bought a Prius!

 

Click and Clack the NPR car guys used to say premium wasn't even necessary in cars that required it. If the engine doesn't use it why pay for it?

 

oh for pete's sake

it was a typo. take off your tin foil hat - there is no conspiracy. there isn't even an 88 octane option here in the states. DO NOT suggest we mix a half tank of 87 and a half tank of 89, as some have crazily suggested on these very pages.

always use the lowest octane the manual says - there will be no increased performance or avoidance of damage, especially in a prius, in fact the opposite is likely

 

Actually, a tinfoil hat WILL increase your MPG.

 

Shiny side in or out?

 

out!

if it is "in", all the bad rays that get in will try to get out but bounce against the shiny side, and the result will be more new threads about 88 octane

 

And heaven knows we don't need that!

 

My 2010 Prius came with a tank of Shell 89, E10; I tried straight gas; and now run Shell 87, E10 and am very happy. The following hill climb test shows the effect:


The higher octane, E89, worked best at the highest power settings going up the hill. However, until the 'plateau,' the E87 gave better mileage, more power per unit of gas. Since you live in a state not known for hills and mountains, I would recommend E87. If you are going to the mountains and want to 'drive fast,' then E89 may let you scoot up the hills faster.

Two years ago, I tried E93 and was not impressed. It seems to have low energy level but the 1.6L engine self-tune was modest, 1-2%:

I haven't tried it with the 1.8L, ZVW30.

Bob Wilson

 

We've beaten this topic to death. Here is a search showing all of the postings:

Google

Tom

 

In the post one of the moderators decided to close, my main point was that 87 octane, with 10% ethanol, is not the same, combustion-wise, as 87 octane with no ethanol, and to get a true 87 octane is it not prudent to use 89 (plus).

While the typo may have been corrected, the essence of the discussion has not.

 

It makes no cents (pun intended) to use any octane other than what is recommended by the manufacturer - which for the Prius is 87 octane. Using a higher octane will not make the engine last longer or run better.

For example, my 1995 Buick Roadmaster had a big Corvette V-8 engine. After 15 years of driving this vehicle with nothing but 87 octane in it (87 was Buick's recommendation) and over 150,000 miles with not a single engine repair other than new oil and air filters - it would have been a complete waste of money to have gone to a higher octane.

 

:tinfoil3:

Yes. Yes it will. As long as it is aerodynamically shaped. Which is why Danny decided the forum needed a tin foil hat smilie :tinfoil3: