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-   -   Octane placebo or logical replacement? (http://forum.e46fanatics.com/showthread.php?t=952554)

Redwards_13 10-26-2012 12:49 AM

Octane placebo or logical replacement?
 
Don't flag me for this question, because I'm obviously well aware that simply putting in 93 octane is the better option, but the gas costs in BC are ridiculous and as student any attempt to preserve money makes logical sense to me. Which brings me to my question, is putting in 87 octane fuel with an octane boost a suitable replacement for 93 octane fuel? Or is it simply just a placebo effect that these companies are trying to exploit?

peytonracer4 10-26-2012 12:51 AM

run 91 minimum.
if you run 87 you'll get slightly less milage per tank. if you run 91 or 93 you'll get slightly more per tank but you'll be paying more.
essentially it's all going to even out so you should run a min of 91 for piece of mind.
hopefully you understand.

the octane booster stuff does nothing and won't help you. the e46 is known to accept 87 however search for "why bmw's require 91 octane" and "pre detonation from lower octane gas" and you'll understand better

Zell 10-26-2012 01:01 AM

High compression engines require high octane. When you compress things, they get hotter, and a higher octane rating will prevent spontaneous combustion from compression. If you use a lower octane, your car will compensate, but you will lose gas mileage as a result.

Redwards_13 10-26-2012 01:04 AM

Quote:

Originally Posted by Zell (Post 14848120)
High compression engines require high octane. When you compress things, they get hotter, and a higher octane rating will prevent spontaneous combustion from compression. If you use a lower octane, your car will compensate, but you will lose gas mileage as a result.

Okay but isn't that what an octane booster does? Increase the octane? So what's the difference between putting an octane boost in 87 compared to simply just putting in 91 or 93?

peytonracer4 10-26-2012 01:13 AM

Quote:

Originally Posted by Redwards_13 (Post 14848124)
Okay but isn't that what an octane booster does? Increase the octane? So what's the difference between putting an octane boost in 87 compared to simply just putting in 91 or 93?

the octane booster isn't going to spread to the entire tank evenly first of all. second, you don't even know how much octane you're adding, if any so it's useless.
and while you're spending like $5 on that bottle every fill up you could just be putting in the 91 octane cheaper.
just trust us, running 87 will not save you money. it will only piss off your car.
you'll get worse gas milage which will even it out, or maybe even cost you more money.

Redwards_13 10-26-2012 01:22 AM

If you ask me to trust you, I most certainly will, I'm assuming you guys know a lot more than I do (which really isn't much) so I appreciate your input, any idea how much more approximately it costs to run 91 instead of 87? Lets just say you drive 15k/year (kms)

peytonracer4 10-26-2012 01:30 AM

Quote:

Originally Posted by Redwards_13 (Post 14848156)
If you ask me to trust you, I most certainly will, I'm assuming you guys know a lot more than I do (which really isn't much) so I appreciate your input, any idea how much more approximately it costs to run 91 instead of 87? Lets just say you drive 15k/year (kms)

Aren't you a student? That's about as basic as math gets.
Lets say you get 23 mpg average (sorry have to do this in miles) with 91 octane. Generally 91 costs 20 more cents per gallon so ill use my local fuel prices. You're going to get about 21 mpg with 87 let's just say.
So 91 costs $3.40/gal and you drive 7,500 miles per year. That's $1.108.69 per year
87 costs $320/gal and you drive 7,500 miles per year. That's $1,142.86 per year

In my example not only are you spending minimally more to "save" money. You're putting your engine more at risk for long term damage.
I'm not saying your engine will blow up running 87. It won't. What I'm saying is you attempt to save money will NOT actually save money and could potentially cost you money in repairs long term. Not worth it I hope you see now.

My advice to you is switch to running 91 if possible (you gain nothing from running 93)
Replace your air filter, make sure your tire pressures are spot on, and just drive carefully to get the best mileage.
Maybe even run through some chevron techtron if they have that there. Bmw recommends it and I do as well every 20k miles or so.

peytonracer4 10-26-2012 01:40 AM

Also, like I said before, google search pre detonation. And why does bmw require 91 octane
To better understand the whole point behind this. 87 has the potential to explode before spark in higher compression engines which is very bad.

carcus 10-26-2012 02:20 AM

If you are a student worried about gas money.....was a used BMW the best choice? Logical sense to me would be getting a Honda that runs on cheap gas, gets better MPG and cheaper to repair. Just speaking fiscally here since you brought up saving money on gas.

Redwards_13 10-26-2012 02:36 AM

Quote:

Originally Posted by carcus (Post 14848236)
If you are a student worried about gas money.....was a used BMW the best choice? Logical sense to me would be getting a Honda that runs on cheap gas, gets better MPG and cheaper to repair. Just speaking fiscally here since you brought up saving money on gas.

Well I'm certainly no peasant farmer... I've worked since I was 12 years old and managed to make and save about $20000, so I was able to buy a BMW, instead of a 96 civic rice rocket; and no matter how well off you are, you try to save money wherever you try to. I kinda figured that was sort of an obvious point, didn't really expect a snide response but apparently my logic was off. So after taking that one on the chin, I appreciate all the responses who actually contributed some sort of useful information or opinion, and from now on I'll be running 91, and correct me of I'm mistaken, but I assumed that chevron just injected their fuel with techron so if I get gas from chevron wouldn't that constitute me using techron enhanced fuel? Same as the shell "v-power", but I may have just mistooken your statement!

sea6speed 10-26-2012 02:48 AM

Just run a few tanks of each and compare mileage. You won't kill the car, but cost savings will probably be next to 0.

sunsetcoast 10-26-2012 08:17 AM

Quote:

Originally Posted by peytonracer4 (Post 14848096)
the octane booster stuff does nothing and won't help you.

This is what he means: The fine print on the sides of the bottles typically say something to the effect that it will increase ocatane by 5 points for however many gallons it is rated for. In real life, this translates into: moving the ocatane rating from 87 to 88 requires 20 bottles.


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