What grade gasoline do you use

<div class='quotetop'>QUOTE(cairo94507 @ Apr 22 2007, 03:04 PM) [snapback]427870[/snapback]</div>

LOL

Actually, before I bought my Prius (last night), one of the things I was considering was a GTO that had been modded, shook like a wet dog at idle, and made way more than the stock 400hp (but what a thrill). I'll explain elsewhere how I arrived at deciding between a GTO and a Prius, though.

On the other hand, it is about time to add some gas to the car, and I wanted to check about such things as ethanol and octane before I did so. Considering the little, dangerous bit I really know about Prius engineering, I felt caution to be necessary.

 

This thread was/is AWESOME! Not that it matters but a quick breakdown of why certain cars need higher octane gas (real quick breakdown because you probably don't want to read much like me)

Most car engines have four strokes: one of which is combustion
Higher octane means it combusts at a higher temperature
More performance based motors run at high temperatures
Hence the reason for higher octane

THERE IS MY SYLLOGISM

If you want me to expand I will do so a little here. Four stroke motors have pistons that have four strokes. During the compression stage, which is one of the strokes, and right before the combustion stroke, the gas is compressed. The higher the octane rating, the hotter the gas has to get to explode (combust). If a motor is knocking, it means the gas is exploding during the compression stage. If the motor does not knock, you can put as low octane as you want until it starts to knock...and your mileage would stay the same. That is all octane means.

I don't feel like typing anymore. But why do I know this? I rebuilt my 1971 camaro from the ground up, including the engine. And I had to read many a book to be able to do that.

 

This thread was/is AWESOME! Not that it matters but a quick breakdown of why certain cars need higher octane gas (real quick breakdown because you probably don't want to read much like me)

Most car engines have four strokes: one of which is combustion
Higher octane means it combusts at a higher temperature
More performance based motors run at high temperatures
Hence the reason for higher octane

THERE IS MY SYLLOGISM

If you want me to expand I will do so a little here. Four stroke motors have pistons that have four strokes. During the compression stage, which is one of the strokes, and right before the combustion stroke, the gas is compressed. The higher the octane rating, the hotter the gas has to get to explode (combust). If a motor is knocking, it means the gas is exploding during the compression stage. If the motor does not knock, you can put as low octane as you want until it starts to knock...and your mileage would stay the same. That is all octane means.

I don't feel like typing anymore. But why do I know this? I rebuilt my 1971 camaro from the ground up, including the engine. And I had to read many a book to be able to do that.

 

All the gasoline in my area comes from the same refineries and through the same pipeline. The only difference is the brand-specific additives package. I'm a cheapo and just get the Costco gas, regular 87 octane. I've used it in several different vehicles and have had zero problems with it.

 

I drive luxury cars before i got prius so i'll just tell you which gas station has the better drive performance to me. Shell is better compared to 76, chevron, arco. MPG, i am not really sure, but the drive is better with shell, and the mpg is probably better or similar.

 

Social Responsibility Rankings for Gas Stations (click link for chart)

g Plus'​

Global Warming Minus'​

​

 

LOL you guys are great LOL

I don't use any octane .... HMMM.. LOL....mine is used with magic

 

Well there seems to be a trend... I drive a lot and Shell gas consistantly gives better mileage than any other station brand name or not. And always it is a better bang for your buck (pun intended lol).

Shell is 90% of the time more expensive, but 100% of the time you get better mpgs that 100% of the time offset the cost. Seems like a no brainer.

In my old 2001 Honda Civic I could see a 5-8 mile per gallon difference between using cheapo gas and Shell Premium (91 octane in high elevation). That is pretty substantial... I have only had the Prius filled up 5 times since I have bought it 2 weeks ago, but again it seems like Shell Premium is doing its thing. For kicks I put in Shell 85 this time to see what I get, but if it isnt within a few miles then it is back to the good stuff.

 

Without any hard data I'd have to take this anecdotal evidence with a grain of salt for the following reasons:

1. You mention high elevation driving which is about the only situation in which higher than manufacture required octane may improve MPG.
2. Without knowing the specific condition of your Civic we cannot determine if the octane made a difference because the car was in poor running order and required the higher octane to prevent pre-ignition and retarded timing.
3. You have no data to back up the claim. It's just a claim.

I'm not slamming you in any way here. I am just skeptical that higher octane would provide such a large MPG increase on a properly running car, without major carbon deposits or whacked air/fuel ratio, in normal conditions. The high elevation could be the key here though due to atmospheric oxygen density and vehicle load.

 

As a resident of the Midwest, I refuse to buy BP gas. Even though they rate #2 on F8L's list.

BP dumps mercury in lake - chicagotribune.com
BP gets OK to dump mercury into Lake Michigan - USATODAY.com
BP gets break on dumping in lake - chicagotribune.com
BP to dump more toxins in Lake Michigan - UPI.com
Chicago Gets BP To Reopen Lake Michigan Discharge Permit Discussion : TreeHugger
BP to Lake Michigan Residents: We Feel Your Pain, But We're Dumping Anyway - Chicagoist

 

The car is a perfectly maintained 2001 that had 50k on it when I bought it, and now has 120k+ works like new, no knocking, no abnormal sounds, always maintained by the dealer. I live at 9000ft above sea level, and generally drive the car between 7000ft and 10,000ft altitude.

Measuring my mpgs I fill it up to the auto-stop from the same station and same pump (most of the time) and always have my tripA set between fill-ups. 26-29 miles per gallon city/highway 75/25 driving with the cheap crap and never below 30 with the good stuff, generally around 32-34. Same driving standards over the past 5 years with the same car, same terrain and similar driving style.

I also drive across the US twice a year from Colorado to Ontario. Shell Premium always gives us better mpgs (whether it be 91, 93, or 94 in various states) as well as PetroCanada 94 in Ontario. This is in all of cars that have done this trip including:

2001 Honda Civic, 2003 Lexus RX300, 2007 Lexus RX350, 2005 Honda Civic Hybrid, and even a while ago in our 1999 Chrysler Town&Country (last time we bought "american").

I can without a doubt guarentee these are factual results. I deliver in my vehicles, and therefore am in them for 5hrs+ a night. Driving 2000mi+ trips cross country also proves this in varying elevations.

Also everything that I have been told, the octane rating is LOWER in high altitude than at sea level. For instance there are various stations that offer grades starting at 84, but generally around 85, up to 91. Lower octane ratings in high altitude should match performance of higher octane in low altitude. So my 91 is like your 93/94.

 

Now think about how bad the rest of them are. lol

 

Do you guys have the Shell Mastercard which gives you a 5% rebate on gasoline purchases? I do and it's nice to get that rebate on the monthly statement.

Note that the Prius tech training docs recommend 87 octane; higher may result in no-start issues. See p. 3-4 of the Hybrid13 Fuel and EVAP System.pdf file here: Automotive Training and Resource Site

 

I've had my 2009 Prius for just over a year now and when I was a Newbie I was all over this site and learned a great deal about how to maximize the MPG's. One of the tips was that 87 octane gas will yield better MPG's since the Prius ICE is tuned to maximize efficiency and not performance. However, just for kicks, I tried 92 on my last fill up and with 140 miles on the books so far, I'm getting a noticeable INCREASE in MPG's. I bought from the same filling station (Safeway) and the weather has been the same and my driving is the same, but I went from 42's with 87 Octane to 46's with 92 octane.

Weird, but true. Now I just have to calculate MPD: Miles per Dollar...

 

Most likely your 92 does not contain ethanol. Any gas with ethanol will deliver less mileage due to the lower energy content. This is not a function of the octane, but a function of the fuel type.

Tom

 

Actually I think your next steps are to track this over time in a more scientific way and with plenty of data.

 

No, I dont have the Shell card. I thought about it, but quite frankly dont know how I would actually pay it. Meaning the only credit card I have is through my bank. All bills are automatically paid online, and I transfer money to my credit card every month online to pay it off (in full!). I have never written a cheque, or know how I should go about paying another card unless it could be linked to my bank account. So I just use my one card and that's that.

 

Plus, experience over 140 miles means very little. Unnoticeable changes in conditions or unconscious changes in driving style can significantly affect MPGs.

 

Well, I'm at 190 miles on the tank and I'm still at 46.3. Very interesting...
Imagine what I'll get in the warmer summer months.?!

 

Woo hoo! :_>