Decalin use in a unleaded mogas - Avgas mix

[srclink]

I just purchased some Decalin to use in my Rotax 912. I always use premium unleaded when it's available, but will be using the Decalin on longer cross-country flights and using 100LL. If I have a 20-Gal tank with 10 gallons of premium unleaded in it and I add 10 gallons of 100LL, should I use 1/2 oz of decalin for the amount of 100LL added or one ounce for the full 20 gallons in the tank?

[MovingOn]

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[srclink]

That's what it says on the bottle and I would tend to agree logically. If you always add Decalin this way to a tank that only contains 100LL, then the concentration would always remain constant with respect to the amount of lead in the tank. However, if there is mixing of 100LL and 91 octane, then the concentration would be diluted (e.g. by the 50:50 mix in my example). Not sure if that's important.

[MovingOn]

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[Merlinspop]

I suppose it depends on the chemistry of how it seeks out and attaches to lead. I wouldn't venture to even guess.

Decalin Chemicals has a contact page on their website. I would think that they could give you much more informed guidance than anyone here.

http://decalinchemicals.com/contact-information/

Do pass along any feedback you get, though, please.

[MovingOn]

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[Merlinspop]

There are people here who know. It's a common issue for LSA.

My apologies to any Chemistry PhDs on here.

[roger lee]

If I add 100LL to my fuel even though I may have 91 oct. in it I just add my 1/2 oz.( per 10 gal) Decalin whether it needs it or not. Why nit pick over 1/2 - 1 oz. It won't hurt anything. I'm usually adding 10-20 gals to top off any way.

[MovingOn]

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[srclink]

I tried emailing Decalin Chemicals this AM before posting here, but their web pages weren't coming up for some reason. Contact link seems to be working now, so I just sent off the question to them. I'll post their reply when I hear back from them.

[3Dreaming]

I'm no chemist, but I would add the Decalin in ratio to the 100LL being added per their instructions. The fact that you are adding the 10 gallons of 100LL to 10 gallons of unleaded doesn't change anything. You still have 10 gallons worth of lead and the correct amount of Decalin to remove it.

[roger lee]

Decalin can be used from 1/2 oz to 2 oz. per 10 gal of 100LL

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[FastEddieB]

I'll join the chorus of "I don't know", but...

...it was always logical to me to add Decalin in proportion to the amount of leaded fuel added.

So that's how I've always done it.

[srclink]

Thanks all for the feedback. Just letting everyone know...Decalin never responded to the question.