Years ago when we used to have high compression big block oldsmobiles and ran into detonation issues, we would doctor up the fuel a little bit with a few tablespoons of trans fluid per tank or marvel mystery oil. I don't see any potential issues doing this on a newer vehicle other than with the O2 sensors or catalyic convertors possibly getting gummed up or plugged. What do you guys think? With the "dryness" of ethanol gasoline these days, and the fact that it's getting harder to find non-oxygenated premium fuels around the twin cities metro area, I am considering blending 87 octane fuel with transmission fluid to get a custom blend that works well for my truck. Before this thread gets off on the wrong track with "Why don't you just buy 92 Octane instead?" The answer already is that in Minnesota, the 87 octane gas has the least amount of ethanol in it. The higher octane fuels such as the 90 and 92 have a higher ethanol content (since ethanol doesn't burn as easy) and is harsher on the motor and fuel system than we'll say a 87. Also with gas prices I'm finding it harder to find "fresh" 92 octane fuel as well, 87 octane tankers come and go but I never see midgrade or high octane tankers but maybe once every couple of weeks. Without using anything funky like toulene or paint thinners, I want to be able to walk into a walmart and buy a quart or two of cheap trans fluid and doctor a few tablespoons up with my gas. If it's sensor and or convertor safe.

 

I have used the tranny fluid to lubricate dry mixed higher octane fuels in the past with no harm effects, but it was an OBD-1 system.

As far a Ethanol based fuels I really can only go off what info I can find on the net. Here in the DFW areas we have the 10% mixture for all of our octane ratings, so I don't know what the higher percentage mixture are like. My 2000 Silvy seems to run fine off the 87 octane with the 10% mixture as does my 2004 Tahoe, but the Tahoe is a Flex Fuel model.

Here is just some info I found:
Ethanol is increasingly used as an oxygenate additive for standard gasoline, as a replacement for methyl t-butyl ether (MTBE), the latter chemical being difficult to retrieve from groundwater and soil contamination. At a 10% mixture, ethanol reduces the likelihood of engine knock, by raising the octane rating.

Here is the link were I found this information:
http://en.wikipedia.org/wiki/Ethanol_fuel


One guy I know will buy 92 octane mix it with toulene and add in the tranny fluid. He mixes it in a farm type fueltank in his garage. I don't mess with this at all, but he doesn't seem to have any problems with it. Although I do believe he has deleted the rear O2's.