I have heard the alcohol causing the "O" ring deteriorization. I fly a Superior 0360 motor that is certified to use 91 octane pump gas with no alcohol. I mix 50/50 91 octane with 100LL and have no trouble with detonation or plug fouling nor can tell any difference in power. In my '52 C170 with the C-145 engine I burned straight 100LL and sometimes sometimes had lead fouling of the bottom plugs. I read some stories about what was used in the radial engines of WWII. They used Marvel Mystery Oil at about 4oz/10gal of fuel. I tried this mixture and I could go over 100 Hrs. without losing a plug. This is a good top end lube and it will show up on the valve stems as a fine coating...no stuck vaalves. I now use this mixture in the Superior engine with the 91/100LL mixture even though I have had no plug fouling problems. Since my engine was still under warranty I called the Superior factory to see if this would affect my warranty...they said no. There are several Continental engines in the area that now use MM oil.
A quick check that I do for testing for alcohol when I buy gas is use a pint Mason jar with about 3/4" of water in it, add about 2" of gasoline, shake well, and then let it sit for about 2 minutes. If there is no alcohol the water and gasoline will separate and there will be a distinct line of separtaion. The gasoline can then be poured off without disturbing the water...I put it in my '59 John Deere 730 tractor which has a sediment bulb for water separation. If there is alcohol in the gasoline, the line will be not well defined and it will have fine water bubbles in the gas and fine gas bubbles in the water.
Burning car gas does save a few bucks.


PS: the Superior factory guy said if I burn straight 91 Octane I should back the timing off a few degrees.

1954C180 wrote:On another board (or was it here?) I saw a comment about how
at refineries, ethanol is the last ingredient added before they
pump mogas into transport trucks for delivery. In theory then at
least, there should be an "ample supply" of ethanol-free Mogas
available at your local refinery which can be transported / delivered
to airports for use in STC'd aircraft that don't require 100 octane
fuel. ...

Ethanol is mixed with gasoline at "terminals" just before it is loaded into the delivery truck. Refineries usually put gasoline in a pipeline to terminals or railroad tank cars or tanker ships. There may be a terminal collocated with a refinery in some instances. An oil refinery would have nothing to do with ethanol, it is not a petrochemical product and oil companies will not mix ethanol with gasoline to ship through a pipeline because they maintain that it increases corrosion. Don't know if it does or not but that is what they claim and it is their pipeline.

In the case of Oregon, there are two major terminals in the whole state, Portland and Eugene. The Portland terminal is at the southern end of the Olympic pipeline which connects four refineries north of Seattle with the rest of western WA and western Oregon. There is another pipeline from Portland to Eugene. All of the gasoline in eastern Oregon is supplied by the Pasco, WA terminal and the Boise, ID terminal. The pipeline is SLC->BOI->Pasco.

Unblended gasoline is always available at a terminal. There is one wrinkle though. When a whole state goes mandatory E10, then the terminals may order "suboctane crap" according to a gentlemen I talked to about it who works at the Portland terminal. Those are his words, not mine. EAA also confirmed this. This is a blending product that is 82 MON or 84 AKI, and when you mix 10% ethanol you will end up with 87 AKI, regular. There may also be a suboctane product that can be used to make 91 AKI. I'm still trying to verify that. The crux of the problem is that the terminals may no longer have 87 AKI gasoline after a state goes E10 which precludes the EAA STC, although EAA told me that 82 MON is the absolute minimum octane rating of the EAA STC and I could still use it, but it provides no margin. This is why most states just exempt premium unleaded gasoline since it represent less than 15% of the gasoline sold, so anyone needing unblended gasoline will have a source.

qmdv wrote:I believe that the only airport in California to offer Mogas is Modesto. http://www.airnav.com/airport/KMOD Well if they don't, they used to. It can be done if they want to do the extra work.
>...

Tim

Modesto doesn't have it anymore. They hung on a long time, but CA has 5.7% ethanol in all of their gas now and the law just changed to allow them to go to 10% and the terminals are drooling over the blenders credit.

Since it is an agreement between the California Air Resources Board and the EPA, there were no hearings and there are no exceptions. Probably why Modesto dropped it, just didn't have an instate source.

qmdv wrote:I understand that 100LL is the worst thing tht you can put in a Franklin Engine

Tim

You understand correctly. I have to put Alcor TCP in every tank. Have you tried to buy that lately??? There are several other brand name additives that do the same thing such as Decalin but they aren't - ahem - certified. Mogas for me unless I am somewhere requiring 100LL, and then as little as possible.

once&futr_alaskaflyer wrote:>... I have to put Alcor TCP in every tank. Have you tried to buy that lately???

TCP is not in production anymore and it isn't clear that it will go back into production. They pulled it late last year because it had a "packaging" problem. As of 4/25/2008 it was still not back in production according to a pilot who called Alcor.

This was burried on their web site at the end of 2007 and was reported in an AOPA ePilot email in January:

"TCP on Hold: Due to new federal regulations concerning shipping of TCP, this product will not be available for the remainder of 2007. Alcor regrets any inconvenience this may cause our customers."