912S Fuel

[George858]

I have a 2001 Kitfox 5 with a Rotax 912S -- My question is regarding Fuel.
Rotax says that that engine must use premimum fuel. The only premimum fuel we have in North Idaho contains 10% Ethanol ! and Rotax says to not use fuel with that much Ethanol in it. Also I do not know what that would do to my planes fuel system (tanks & Fuel lines) I have heard that tanks could leak and lines could become unuseable ?
The only other option I guess is 100LL which again Rotax does not like because they say it is bad for the engine valves, and the engine in general.
The only fuel we can get without Ethanol here is one station that has regular unleaded.
Can octane booster be used to raise the regular to an octane that compares to the preminum gas or is the need for premimum in the engine not really required ? and the non Ethanol regular could be used
I guess my question is what fuel should I use??
Thanks

[RandyL]

I've talked to several operators of 912S who are running on premium auto fuel with the 10% ethanol in it and they all report no problems. Of course you'll want to make sure your fuel system hoses etc. are compatible.

I know several others also who run on a steady diet of 100LL and as long as you don't use full synthetic oil and keep your oil change intervals shorter they are reporting no other problems either.

Hopefully others will comment on their fuel choice and operating experiences.

[DesertFox4]

100 % 100LL for me. Only tried premium auto fuel with alcohol once and had a bad experience with the fuel dissolving the resin in the wing tanks. This happened after only two tanks run through in about a weeks time. Fouled both carbs so bad the Rotax 912S wouldn't run. Full tear down of both carbs and intense cleaning and then rebuild kits to get them to work again. Almost broke down and bought two new carbs. Never again. I think the Rotax will tolerate it but my fuel system most definately won't.
Using 100LL is not a concern if you do it properly. Use Delcolin fuel additive from John at Kitfox Aircraft LLC. and change oil at 25 to 50 hours of service. My spark plugs have never fouled, ever. They get changed every 100 to 150 hours and come out perfect with a light brown color. The Delcolin works and you can safely carry it in your airplane. The other brand if it spills will melt your paint. Don't ask how I know this. I also use a little Marvel Mystrey Oil to help keep the hydraulic lifters from sticking in every other tank of fuel at about 5 ounces per tank. Seems to work with no ill effects.
Stay away from full synthetic engine oils when running 100LL. The new Shell oil that Kitfox Aircraft LLC. now carries looks like a good choice.

[George858]

Thanks Steve for the reply
George

[George858]

Thanks Randy

[Skybolt]

The only other option I guess is 100LL which again Rotax does not like because they say it is bad for the engine valves, and the engine in general.

Hi George.
I agree with what DesertFox 4 is saying.
About the Shell oil (it even has Rotax on the label).
I also use the Delcolin fuel additive from John at Kitfox Aircraft LLC.

When I was using the super unleaded auto fuel I was getting fuel leaks from the sample valves. The stuff would soften the rubber rings.

When you think about it. With LSA getting popular for training and personal use, Rotax has sort of relaxed on the use of 100LL. They have to or they will not be selling engines for this segment.

Eric.

[wadeg]

For ethanol-free auto fuel, try checking with your state marine board. Here in Oregon, the marine board lists on their website the sources of ethanol free fuel since a lot of boats have had trouble with ethanol.

Also, I buy my eth-free stuff at an oil company. Bought a 55 gallon transfer tank for my truck and just get it filled when I pass the oil company. They sell loads of the stuff for farm equipment and it's popular amongst the yard car folks with 2 strokes.

Furthermore, my truck loves the stuff when I'm too cheap just to go to the gas station and I want to use up "old gas" (at least that's how i justify it)....

[Skybolt]

A friend of mine had to make a landing in a field (with his wife on board)
A Cessna 120, believed it clogged up the carb with stuff breaking loose in the fuel system. This airplane was approved for Autogas. Not the corn mash stuff that is now blended in. Kind of moonshine:>)

No one hurt. Wife scared out of here wits. Much damage to aircraft where it sliced through the fence and pot holes.

Eric.

[dcy92444]

"Stay away from full synthetic engine oils when running 100LL. The new Shell oil that Kitfox Aircraft LLC. now carries looks like a good choice."

I was hoping that you might consider elaborating on this piece of information. I have a KFm 112 and run 100LL but recently switched from 15W50 Aero Shell to Amsoil 5W30. I have found my engine starts better, runs cooler with lower EGT and CHTs. I have heard this about synthetics before but I know that the Aero Shell is partly systentic. So what is the difference? Cold starts are much improved also. This is not a challenge but a request for help and information. Thanks

Dee

[Mnflyer]

Hi Dee, the problem with full syn oils and 100LL is that full syn oils do not scavenge the lead and hold it in suspension as dino oils do thus over time the engine becomes lead fouled. This is why Mobile got sued and removed their Mobile 1 aviation from the market many years ago. And changing oil at shorter intervals is not the total answer as the syn oils just don't remove the lead in the first place thus the lead deposits its self in the crankshaft oil passages and will eventually clog the passages causing bearing failure.
As to why your engine starts easier syn oil flow much better at low temps causing less drag for cold starts, it would be far better to use an engine preheater and semi syn oils IMHO.