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Discussion Starter #1
My M Coupe was running really poorly. Changed from Mobil Premium to Amoco Premium and it smoothed out. Went over to Sunoco 94, and feels like someone chipped the car. I am not a fan of magic oil and such, but the new M seem to just thrive on the extra octane. Try it out.

Tried going even further to 100 octane unleaded Sunoco race fuel, which had little additional benefit. 94 seems to be the magic number for these cars.

Gregor
02 M Coupe
 

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Investigative Tinkerer
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I regularly use Sunoco 94 in both M Rdstrs since getting them.
I only use an alternate brand when there is no Sunoco available.
The X5 gets an occaisional fillup on 94, but usually survives on the 92 variety.

I don't notice the 99 or 01 M Rdstrs running any differently on an occaisional tank of Shell or Mobil Premium gasoline.
 

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into things retro
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Question

Does octane 'average out' when mixed?

For example: Does half a tank of 92 with half a tank 100 give you a full tank at 96?

California and it's monopolies and AQMD (Air Quality Management Dept.) have decied that unleaded premium for us is 91 octane :thumbdwn:

There are some places around the SoCal area where 100 race fuel can be had (at about $4.50 to $5 a gallon)
 

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M Mad
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Re: Question

scottn2retro said:
Does octane 'average out' when mixed?

For example: Does half a tank of 92 with half a tank 100 give you a full tank at 96?

California and it's monopolies and AQMD (Air Quality Management Dept.) have decied that unleaded premium for us is 91 octane :thumbdwn:

There are some places around the SoCal area where 100 race fuel can be had (at about $4.50 to $5 a gallon)
Basically yes.

One thing to realize is every gasoline additive package not only cleans out existing deposits, but they also leave some of their own.

I saw an article by a petroleum engineer who drives a Vette. He switches from one major brand to another every 5000 miles. He will go say from Shell to Mobil to Texaco to Sunoco etc. He feels (and he is in the business) that way the new additive packge will clean out the deposits left by the old package, adn then start leaving its own, so the next switch takes care of those. He uses 5000 miles as a way to make sure that the new gas has cleaned out the deposits of the old, plus it is easy to remember.

So a switch every so often is a good idea. I used to run a couple of tanks of Mobil Super Premium every so often in my other cars to clean the system. It worked. I could see a 1 - 1.5 MPG increase form two tanks of Mobil Super Premium, and the increase stayed for a reasonable amount of time after going back to the cheapest gas.
 

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ooooohhhh .. racing fuel

i have put racing fuel in my 2002 bmw a few times... she runs good already on 91 octane.. but i wanted to see if theres a considerable difference in racing fuel.. as i suspected i was right.. i went to a race shop i know and got like 105-110 octane.. something like that i forget... the color of the fuel is very different then regular gas... i usually get about 180-200 miles on a full tank of 91 octane gas.. with the racing fuel.. the miles were cut in half roughly.. but oooohhh baby.. does the car pull... i cant afford to fill it up with racing gas all the time.. and the place is far from my house.. but if i were to race my friends or people for money.. i would definantly put in some.. the plus side is the car feels so much faster.. but cost a lot and burns up much faster...
 

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zeddy
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Gregor said:
My M Coupe was running really poorly. Changed from Mobil Premium to Amoco Premium and it smoothed out. Went over to Sunoco 94, and feels like someone chipped the car. I am not a fan of magic oil and such, but the new M seem to just thrive on the extra octane. Try it out.

Tried going even further to 100 octane unleaded Sunoco race fuel, which had little additional benefit. 94 seems to be the magic number for these cars.

Gregor
02 M Coupe
Hi Greg,

I buy the high-end gas at the local Sunoco down in Bethel. As the English would say " it works a treat!".

Sharon and I purchased two tickets to the Vintage Fest, hope we'll see you there.

Ed
 

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Lead Foot
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Aviation Fuel?

My planes used 100 Octane Av Fuel. If you can locate a small country type airport that houses old planes they might allow you to fill up. I have seen pick ups come in with 5 gallon cans fill up for their swamp buggies, hah. Strictly legal. Just a thought guys. Price is not $3.50 per gal. Much less.
 

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M Mad
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Re: Aviation Fuel?

rwebbe said:
My planes used 100 Octane Av Fuel. If you can locate a small country type airport that houses old planes they might allow you to fill up. I have seen pick ups come in with 5 gallon cans fill up for their swamp buggies, hah. Strictly legal. Just a thought guys. Price is not $3.50 per gal. Much less.
Don't even THINK of doing this.

Aviation fuel has a very high lead content. It will kill your O2 sensor and your cats. And not be covered under warranty.

Even 100 LL (Low Lead) aviaiton fuel has more lead than auto fuels had in the 60s. Even 80 octane aviation fuel has a good bit of lead in it, over 0.5 grams per gallon.

Also the way that motor fuel (cars) and aviation fuel octane ratings are derived are not the same, so they are not comparable.

BTW Commercial ASMEL IA RH, Glider, Private ASES, CFI - ASE IA RH Glider
 

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Lead Foot
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100 Av Fuel

Sorry guys. Never thought of the hi lead content. Don't use Av Gas.
We used it in our cars during crises or lack of auto fuel and never had any apparent difficuilty some years back. Auto engines have become more sensative of late I guess. By by. I do appreciate being corrected however.
 

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100LL

It worked great in my 72 TR-6 but MR. P-Cone is correct. It will nuke a modern emission system.

Can you run Jet-A in a VW TDI??... JK
 

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Lead Foot
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Jet A in VW D

Well in the way back when days, you could just about burn anything but milk in the stink pot engines. What with the sophistication of the new engines I would hesitate burning anything other than Pump fuel. 94 Octane here in Central FL like Texaco and Shell run special days for 5 o 6 cent discount. Like to-day I need fuel and the price should be $150.9, Diesel is about $1.44.9. I find when my compter reads 40 mile to go, I fill up with 15.4 gallons. The computer is reading average flow of 22.3 MPG. So rather than run out and possib;y burning up the fuel pump I make sure to fill it when 40 mark is reached. When ouit in unfamiliar territory I don't let it get lower than 80 to 100. My cruise went wild the other night and raised from 75 to 83 in a few seconds. Hiiting brake cut it off. On reset it was O.K. Car goes in for Nav work next Monday so I will mention erratic cruise control to the tech and see if he has any bulletins on same.
 
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