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Care and Feeding of the Rotax 912

What I found interesting is that while trying to debunk myths regarding the ROTAX, he propagates one. He discounts using fuel with ethanol for no scientific reason, yet he prefers to use 100 LL given all the problems he notes about it. Both are contrary to other experts and with ROTAX as well. He also discounts using additives to fuel although ROTAX is fine with them. There are enough folks using auto gas that I think we can be assured that our fuel tanks are not going to dissolve right before our eyes.

Different strokes I guess.
 
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I questioned Paul about this. He said he meant he would rather use auto fuel, but can't in his plane because of the ethanol so he is stuck with 100LL. I told him that isn't really what he said or the way it came across. It almost sounded like he likes 100LL over auto fuel in the program. I heard many say that's what they got out of what he said. Lead build up over time can and does get ugly and it is more costly with currently maint. and maint. down the road.
 
There is another reason not to use ethanol gasoline in airplanes: it is not stable and may starts degrading after only one month in your tank. This can typically happen during winter time. Not wanting to take a chance last February with 2 months old full tank, I dump it... into my car tank. I do not want to have to do that again (in addition to the annual that can be scheduled for an empty tank). A fellow RV-12 flier used ethanol gasoline until he found out that he could no more balance his carbs at idle. Reason: deposits in the carb due to ethanol (hobbs at 130 hours). Now he is using only alcool free gasoline. The local flight school at my airport used to fly their Remos with car gasoline they switched to Avgas too. Their mechanics warned me about ethanol gasoline degrading with time. All this is fact based and does not looks like myth to me.
 
Rotax is okay with 4-6 weeks and many go well past 8 weeks. Not my first choice by any means. I tend to fly a lot so 4 weeks would be a long time for me. I go through close to a tank a week. I work on 30+ LSA with Rotax a year and see almost no issues with people using ethanol laced fuel. The engine doesn't care about the ethanol or our fuel hoses. If your fuel tank is good with it thn you should be good to go. Places like Arizona have it all year and we don't have any issues. People from other states that use it that come to see me have not reported any issues either.
The only issue with auto fuel for long periods is the fuel drying in the bowls and clogging the idle jet and if it ever sat long enough can loose some of its octane and additives. If fuel ever does clog the idle jet which takes quite a while it is easy to spot with a set of carb sync gauges and can be remedied right then and there without removing the carbs.
At exactly what week that the fuel changes enough to be a problem may be
anybodies guess unless you sampled it every week and had it tested at a lab to get real results and not someone giving it their best guess. It is far cheaper using auto fuel verses 100LL and not only for the price of fuel ( between $1.75 and $2 per gal), but because of all the increased maint. cost for things like oil changes and gearbox clutch cleaning and then possibly issues with lead accumulation on the valves or pistons that may need dismantling and cleaning.
Nothing wrong with 100LL so long as you understand the additional cost and additional maint. involved and what that truly means. Some people around the world are stuck with 100L and have no other choice.

Most Rotax engines suffer far more from poor maint, neglect or
misinformation than any other cause world wide.
 
We are fortunate to have good sources of clear 92 octane mogas where I am in Oregon. I have left the plane in my hangar for 2 months using clear mogas and stabile with no problem. Last winter I left it 3.5 months with 92 clear mogas mixed with an equal amount of 100LL and no problems. I make sure I fly the plane before leaving it so the fuel is well mixed throughout the entire system.

If I had access only to mogas with ethanol I would feel comfortable leaving it that long (3.5 months) mixed with 100LL 50/50 but longer than that I would want to drain all the fuel and replace it with 100LL. I would not want to leave it completely empty for very long because I would not want gaskets, etc to dry up.

The above is just stating my experiences and preferences.
 
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