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Discussion Starter · #1 · (Edited)
Now that Sunoco no longer sells Ultra 94 octane gasoline has anyone had any positive/negative experiences with after market octane boosters? I recently purchased STP's octane booster but have not added it yet. STP claims that adding one bottle of their octane booster to 16 gallons of unleaded gasoline will increase it one (1) octane point. In NVA I have access to 93 octane (sorry CA :crying: ) but want to continue using 94 octane. I checked previous threads but could not find a real answer. Would anybody care to comment? :blabla:
 

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Hi,

I have a friend who is a chemical engineer and owns an e39 M5, he says that the usage of octane booster is good for the car. It helps clean the combustion chamber, fuel pathways, injectors, etc. He says that its formulation is good enough so as to help remove any gunk in the gas tank, fuel lines, etc. Yet, it´s not abrasive enough so as to cause damage to any rubber or plastic parts. He´s used it for years and says that he has never had any problems.

As an e34 M5 owner, I have also used octane booster on several occasions, and on the dynamo, fellow e34 M5 owners have had an average 2-3hp increase per bottle. Heck, on track days or club events, they´ll put up to 4 bottles in their gas tanks. I´ve done that to my car one or two times, it makes a noticeable difference in accelaration. I´ve never had any problems with it either.
 

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aparently toulene works better and is available at a paint supply store. I heard the octane boost is more like .1 octane per tank of gas.

I have seen toulene in action and it does work. I also thought that higher octane really only helped turbo's cars. 100 Octane on the s4 was like jet fuel.
 

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DrewT said:
aparently toulene works better and is available at a paint supply store. I heard the octane boost is more like .1 octane per tank of gas.

I have seen toulene in action and it does work. I also thought that higher octane really only helped turbo's cars. 100 Octane on the s4 was like jet fuel.
You do have to be careful with "toluene" because it may not be compatible with some of the seals. The dosage is usually about 10% toluene. This is hazmat, so be very careful mixing, use well ventilated area, use of gloves and mask is recommended. If adding directly to tank, I suggest having some fuel on board, add toluene, and then top off with fuel. And yes, on turbo cars, it is pretty amazing, I think this gives somewhere around a 5-6 point octane increase.
Regards,
Jerry
 

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Octane booster only raises your octane .01 of a ron. That is like raising your octane level from 94 to 94.1. So if 5$ is worth it for 1/10th of a point to you then get some! ;) Otherwise go get 3 gallons or Tolulene and put that in. Does the same thing and raises your ron about 3 full points (on average). This is usually more beneficial in forced induction cars though.

Alex
 

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Discussion Starter · #6 ·
Sanity check required here - ouich I just retrieved a bottle of the Prestone 0 to 60 Octane Booster (sorry I though it was STP in my original post :confused2 ) I bought to verify their claim. Prestone claims and I quote " Increases octane by up to 10 points*" in small print it continues with "in regular unleaded gasoline 1 point is equal to 0.1 octane number". Their claimed increase therefore is 1.0 for every 16 gallons of gas i.e., in my case 93 to 94 octane. Is this believable? I don't know. I'm always wary of claims that include "by up to". ;)
 

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Toluene has an octane rating of 114. Simple averages will give an octane rating based upon how much pump gas at a specific octane and the octane of whatever else you put into a specific size tank.

Note....octane is a rating of resistance to premature detonation. Higher octane pump gas isnt adding power, it is pushing the engine to maximum efficient with that specific fuel. Going to a different compound for fuel may (or may not ie ethanol) produce more power.
 

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I've asked BMW mechanics...and he told me it wasnt a good idea... :confused2 ...

I had that probs with my Merc before....It is reccomended to fill with 95ron pertrol, but I thought 98 is better...anyways petrol in Russia not as good as in US or Europe...probably...not sure...

Anyways...my sparks went bad...on a Merc...replaced then...then they went bad again in couple thousand miles..got new ones....and I started to use 95Ron...prob disappeared...
 

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Discussion Starter · #13 ·
gdoan said:
Bruce,
Check out this thread (http://www.m5board.com/vbulletin/showthread.php?t=8479) and its contained link (http://patriot.net/~jonroq/Tech/octane2.html) for an extremely informative look at additives and toulene, in particular. I've used toulene, purchased at Home Depot, in my car and thought I felt a difference and I'm not chipped.

Good luck,
Greg
2003 ///M5 Jet Black/Black, Sport
Beastpower Sway Bar Brackets, Bluetooth, Aux Audio Input & all "+" options except PDC
Thanks Greg, I'll take a look at it!
 

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4ocious said:
Now that Sunoco no longer sells Ultra 94 octane gasoline has anyone had any positive/negative experiences with after market octane boosters? I recently purchased STP's octane booster but have not added it yet. STP claims that adding one bottle of their octane booster to 16 gallons of unleaded gasoline will increase it one (1) octane point. In NVA I have access to 93 octane (sorry CA :crying: ) but want to continue using 94 octane. I checked previous threads but could not find a real answer. Would anybody care to comment? :blabla:
I haven't seen Ultra 94 in NY in quite some time. Was in PA. yesterday and went to a Sunoco and they did have both 93 and 94
 

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i've got 2 gallons of toulene and 2 gallons of xylene lying in my basement. Which one is better?
 

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I know in S. Calif. a few select 76 stations sell "racing fuel." They sell two types; 100 oct. unleaded and 110 oct. with lead. The fuel is in 55 gallon drums on the premises so bring a container they can pump it into. The cost here is approx $5 a gallon. Obviously the unleaded is the only choice for our cars. I have run 110 with lead exclusively in my KTM dirt bike with excellent results. Just some more food for thought on this topic. Good luck. :cheers:
 

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There is way too much info on the net about this , So you can pretty much make an informed decision about it. Just google for homemade octane boost or words to that effect . you should get get enough info to decide what to do.
 

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Octane ratings and the RON numbers are sometimes difficult to evaluate in modern engines (the tests are based on how fuel behaves in a 'standard' variable compression engine)

However all engines like higher Octane fuels. In the UK we have 97 Octane and a very good fuel called Shell Optimax, shell optimax is a high octane fuel that measures closer to 100 Octane and I find this offers a noticeable difference to how sweet the M5 runs. In theory if the M5 was mapped for moderate fuels pushing the ignition map and adding advance should add a little more power is the fuel is up to it.

I know the M5 does some self mapping but I suspect that there will be a target curve that the M5's knock sensors work towards, so In guess there will be an octane rated fuel above which the M5 will not take advantage off unless it is remapped to do so.

Anyhow I notice a difference in grunt, and sweetness with Shell Optimax :wroom:

this is close to 100 Octane (according to some race engineers I know) and the M5 pulls harder and sounds less stressed buzzing round to 7,300. I have not dyno'd it but I would liken the difference to some of those cold morning crisp air feelings. It just feels sweeter and stronger ;)

I know people who have found hp using Shell Optimax, but no figs for the M5

Shame UK fuel is so darned expensive..... Optimax is well over 80p per litre
 

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is it ok to fill the tank with 100 octane or should i mix 91 octane or lower to mix it? will the car become reliant on the higher octane, or will have any bad long or short term effects(bad)?

76 station in san jose has 100 octane gas.

:wroom: :viking: :M5eyes:
 

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Carrera2RS
In the states the RON and MON are added and then divided to get the octan e rating for the US. In Europe its just the RON octane rating used. So basically a premium unleaded fuel rated 98 RON octane number in Europe is equivelent to 93 octane rating in the US.
Just a tid bit of info to pass out.

(R+M)/2
 
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