I think the manual says 91 octane. Is this what we should use? Why so high octane? What would regular 89 cause?. Ron

 

I have been running regular in mine for over a year now with no problems. Did have 1 tankfull out in Iowa with ethenal that seemed to cost a lot of power and smoothness. Only time ever used hi test has been at dragstrip, which was more years than I care to count.

 

I run premium where the rating is 93 where I fill up. Since the cost difference is only $.10 more than regular where I get mine, I just don't see it necessary to go with the lower grade. I will say when I was out of state recently and came across a station that if I remember premium was only 89 or 90 and didn't have ethanol, my gas mileage improved about 3-4 mpg.

I've heard of people only running regular but every 4th fill up they would go with premium and never saw any ill effect, but that is a far cry from a structured test to determine any impact.

Now on that note, I find it interesting there appears to be a correlation between the requirement for better MPG of automakers, which impacts the oil industry, and the fact that more and more cars are starting to say you need to run higher grade gas. While many will say it is because the engines are better and you need to run the high grade, I still wonder what relations these two industries have.

Maybe we need the myth busters on this

 

I've mentioned this before, but I almost always use 87 regular. no issue, no knock, no perceived performance degradation, mpg about 25 in normal commuting. Premium here is like 20-25 cents higher, and I'm seeing no reason to use it for how I drive. Usually at the station I go to they have 89 for the same price as 87 so I use that, but if not then the 87 is just fine. I have noticed though that with the return of colder weather my mpg has dropped about 2 to 23 rather than the almost 26 in the heat of the summer. That happens with my bike too, and that FI doesn't care for colder weather. I don't either, and carbs aren't as efficient in the cold either, but it has been a noticeable drop. I wonder if a higher octane in cold weather would be better. I may try that on the next fill just to see.

 

I use premium only in mine (91 or 93)... To me the manufacturer requires it and it isn't worth the extra $2-$3 per tank difference between regular and premium for me to fuss about when 87 octance has a chance of causing problems...even if slim

 

Do You Really Need Premium?

 

If nothing else, make sure you read section 7.5.
7. What parameters determine octane requirement?

 

Sounds like a variation of gas octane will work. I will probably stick with the higher octane. Ron

 

I read it all, THIS was of most interest to me:

The use of fuel of too low octane can actually result in both a loss of fuel
economy and power, as the management system may have to move the engine
settings to a less efficient part of the performance map. The system retards
the ignition timing until only trace knock is detected, as engine damage
from knock is of more consequence than power and fuel economy.
This tells us that engine damage is not a big concern, as the management system will compensate for cheap gas. But it also tells us that we may not save anything after all, by buying cheap gas.

I'll do my best to save a buck on oil filters (WHEN I can find fleece filters in a local store) and on oil (by buying 0W40 at WalMart).

Other than that, I'll stick with premium gas.

 

Try this when you need an extra boost. It's like $20 bucks a can and can stretch to a couple of tanks if your just looking to get to 95 or so. Normally is half to 5 gallons for 105 octane. Many of you do not need anything close to that. Way cheaper than to buy race gas.
Torco Accelerator

 

I think I'll stick with my testosterone shots!

 

I only put 93 in mine.

 

Shell 93 V-POWER here.

 

Colder weather will let you get away with a lower octane fuel
Octane has nothing to do with miliage but, with electronic retardation systems the EMS may run a richer, less fuel efficient mixture.

Ethanol will also give you lower mpg's as it contains less energy per gallon. However it improves Octane and allows for the cold air compression increase. Each engine map will operate differently Ford, Lexus, Camry etc but our little 3.2's ought to operate the same.

I'm surprised MDaniels gets lower milage in cold weather. The fuel should be denser as well as the air yet it should pack more power per gallon and per Cubic feet of air volume. Perhaps he is running rich to compensate.

I used to get 27 MPG highway. After my tunes I get 29.5.

Shell v power 93 unless I can't find it.
BP 92 seems to run fine and give me the same milage.

I run sans Ethanol whenever I can. It is simply immoral to burn food in our cars.


roadster with a stick

 

We are stuck with 91 octane for premium in Colorado (and even 90 is some locales). It's very hard to find non-ethanol gas here. Of course we have 85 octane for regular gas (due to our high altitude) as well.

I always put premium in and have no worries.

 

I think I'll have to buy high octane 91 and look for non-ethanol gas. Thanks Ron

 

Higher compression engines require higher octane. However, the marvelous ECUs in our cars will retard the ignition to prevent damage from pinging (pre detonation). That being said, I won't use anything less than midrange octane and often alternately fill with midrange and premium when tank is 1/2 full.

 

Just to set somthing straight. I bought Fuel at a place that always carries good fuel. Filled up and 20 miles into the drive check engine light started flashing and car ran like CRAP. missing jerking you name it didnt think I was going to make it to the next offramp. Got it to my shop and hooked up the scanner and had 16 codes all misfires every cyl. except 4. It burrned 1/2 tank of gas in 40 miles??. so Put in a bottle of rubbing alcohol in the 1/2 tank I had left. Ran good after. Went to the station and topped off with 100+ octane and now cant stop her. STAY WITH WHAT YOU KNOW.Octate is the KEY!!!!

 

sounds like a little ground water got into that tank....lol....we have a very smart car, and it will compensate, and remember...feed a dog cheap food and he may not bite you, but he may not be your best friend either, feed him right, and he'll love you to death...our cars run best on the octane recommended, simple as that. Why make it retard all the time and burn that memory into the computer? I still think it harms the engine with more heat and stress over time, like when you get into the 80-100K range...just me...

 

Years ago we put in dry gas if water got in the gas. Is rubbing alcohol the same thing??? Ron