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Decalin approved?

Yes Decalin is okay to use in the Rotax engine. Rotax just doesn't have any real test data to offer.
I highly recommend that if you use 100LL then you should use Decalin religiously.
If you can stay away from 100LL you're far a head of the game. 100LL is damaging because of accumulation over the life of the engine no matter what. Use during cross country's are such a small percentage of most fliers total time over the life of the engine it isn't an issue, but Decalin should be used.
 
I've been using Decalin (at 1 oz per 10 gallons) and burning nothing but 100LL for over 600 hours in our New Blue RV-12. Lead has not been a problem. But then again, we change oil every 33 hours, purging the system plus removing and cleaning the tank. There is always an accumulation of lead in the tank.
 
Mitch,

I'm curious as to how you know it's not a problem unless you've opened the gearbox to inspect. My understanding is that he gear box and clutch are the parts that most susceptible to damage.

Rich
 
If you use 100LL you have lead build up. There is no way to get around this. It just becomes a fact of life. There is no way to remove all lead. Decalin just helps reduce it. At 600 hrs. you are supposed to remove the gearbox (spelled out in the Line Maint. manual) and have it cleaned. At about 800 hrs. your gearbox clutch won't work any more because it will be packed with lead. I have seen many, it will be there. The clutch must be dismantled and cleaned to remove the lead. this can only be done at a Rotax distributor. Lead will deposit on pistons, rings, inside the gearbox and valve train parts.
 
MLock said:
... we change oil every 33 hours, purging the system plus removing and cleaning the tank. There is always an accumulation of lead in the tank.
Click to expand...

Mitch do you have a process/pictures of this process?

Thanks,

Bob
 
Rotax Webinar tonight at EAA.org!

For those who would like to learn more about their Rotax engines there is an EAA webinar titled, " Care and feeding of your Rotax" tonight at EAA.Org at 7pmct. :D
 
Lead isn't just in the oil. The burning inside the cylinders leaves deposits. The guys who fly at low rpms have far more build up.
 
Sorry I don't have pictures of the process. A Rotax certified mechanic does just about all the maintenance work on the engine in New Blue. He just does the job with no pictures.

I did have the gearbox rebuilt at Lockwood this past January while at the Sebring Expo. They showed me the interior. There was no excessive lead build up.
 
The EAA webinar last night seemed to contradict the conventional wisdom about avoiding leaded gas. The presenter, Paul Schuch, said he prefers 100 LL over auto gas to avoid the "corrosive" effects of ethanol, and that Decalin should be avoided because it carries the lead into the exhaust system causing cracking.

I didn't agree with much of what he presented, but you know what they say about opinions! ;)
 
They have pulled Rotax engines apart that have used 23% ethanol auto fuel with 1500 hrs. that had no ill effects. Paul really should have done a better job in his pre-presentation research. I think he was off base. The lead alone will not cause cracking in a stainless steel exhaust system without some help from an owner doing the wrong things. Rotax has more than 23 years of lead use, auto fuel with and without ethanol in their engines from around the world. Millions of hours. Paul should have contacted the right people for his research. For me, I think I'll stick with the proven Rotax test research and 23 years experience. Lead has always been detrimental in all engines, but some had to have it and there was never an alternative until recent times.
 
I come from the nuclear industry where the extemes of temperature make it imperative that we maintained water chemistry to the ppm and ppt level of contamination. Lead is a particularly bad actor in the high temperature and stress environment for stainless steel and nickel allloys. Leaving a lead shield blanket in the primary coolant circuit cost a Belgian plant about $500M when it destroyed their nickel alloy steam generator tubes. Thew only time lead is good is when it`s between me and gamma rays! :D
 
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