The International Cessna^® 170 Association

George-
Look at the picture of the RED bottles, it IS isopropyl. The YELLOW bottles are methanol. Big difference but point well taken. Don't use methanol.

Thanks, Richard. Yes, I see that. The message I posted described "HEET"...not "ISO-HEET".

HEET was once promoted (improperly, in my opinion) in an article by one of our Members. The HEET AUTOMOTIVE GROUP is still not an aviation approved supplier, nor do their instructions properly provide a method to achieve the allowable 1% mixture. If I didn't fail in my math, they offer a 3% mixture by direction, except that they don't reveal the other "anti corrosion" ingredients in their product, or if those are compatible with aviation use.

Each to his own as regards such products. Some are useful in the practical sense, I agree, and I don't fly in Alaska where FAA often turns their head. I also have never had a fuel icing problem so I'm not a promoter in use of HEET products, but alcohol does promote fuel system deterioration and corrosion so I avoid it. The gascolator design of our airplanes also isolate both water and ice from entering the carburetor anyway.

The Cessna Service Information Letter SE79-30 dtd 6/18/79 permits the use of isopropyl in a ratio of 100:1 for fuel anti-icing purposes. For a 170 with 37gal useful fuel, that equates to 1.5 pts/wing or 3 cups/wing or .7 L/wing. Mix well

pdb wrote:The Cessna Service Information Letter SE79-30 dtd 6/18/79 permits the use of isopropyl in a ratio of 100:1 for fuel anti-icing purposes. For a 170 with 37gal useful fuel, that equates to 1.5 pts/wing or 3 cups/wing or .7 L/wing. Mix well

That would be Two, 12 oz bottles of Iso-Heet per wing....if they were 100% Isopropyl (the anticorrosion inhibitor removed.)

If you want to use 100% anhydrous isopropyl alcohol rather than something like Iso-Heet, the most readily available source I know for pure anhydrous isopropanol is TechSpray 1610-G1 sold online by Allied Electronics, among others. It's 99.8% pure anhydrous isopropyl alcohol and goes for about $30/gal. There may be other sources for the stuff, like on Amazon, but I'm familiar with this one.

It's available from SkyGeek for $14.20/gal., but shipping is expensive.
http://www.skygeek.com/isopropyl-alcoho ... As2M8P8HAQ

It's available from many paint and industrial supply houses also.

Yeah George, I wasn't sure that stuff sold by SkyGeek was anhydrous, so I didn't mention it. Glad to know you think it is. It's significantly cheaper.