The operations and maintenance manual don't really list the 100LL for the 350i.  It is listed as an alternate fuel of 100LL for the 350iS.  Additionally, there are instructions to have synthetic blend oil and change it more frequently.

So very difficult to find airports that carry MOGAS or AV100UL (or any unleaded fuels)

Has anyone used 100LL in the 350i and did you use any additives like decilon(sp)?

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From the ULPower web site page for the 350i:

"Regular unleaded automotive gasoline with min. 95 Octane RON ( 91 AKI)
AVGAS 100LL may also be used if regular fuel is not available. NEW UL350i (with serial number above 223501 ) engines can run on MoGas 91 RON fuel (87 AKI)"


I live in snow country and try to go south in the winter. When I do I end up using Avgas. It works. The 350IS, which is basically the same engine with higher compression must use Avgas. If you use Avgas you must use aviation engine oil. Automobile type engine oils no longer have additives to deal with lead. UL recommends using Aeroshell 20-50 and to change your oil more frequently when using Avgas instead of Mogas. Aeroshell already contains the additives to deal with lead. No additional additives are needed and are not likely to improve the formulations which have been developed and tested extensively by dedicated experts at Aeroshell. Avgas turns your engine oil black vs the light brown when using Mogas, ugly but is just carbon. Engines have been running on leaded gas for decades. Lead does contribute to fouled plugs so use Mogas when you can.

At home I use ethanol free premium as it is a little more stable than fuel with ethanol and is less likely to cause grief with my rubber fuel lines. Modern rubber fuel lines are supposed to be compatible with ethanol, but why tempt fate? UL says their engine can use fuels up to 14% ethanol.

FYI, Rotax addresses the lead issue in a similar fashion to UL. They say to reduce change oil intervals in half when using Avgas and to go fly. Rotax engines use a remote oil reservoir which makes the use of oil additives to aid in transporting lead even more important. 



Thanks for information.  The fuel burn at cruise is nice at 5 GPH, but the cruise speed is around 75 KIAS.  So I don't plan on big cross country flights, but you see it's tough to fly more than just a few hours with 2 people due to reduced fuel load (empty weight 852, me (220) and passenger or camping equipment (160) and fuel) to keep with LSA or even 1420 for Experimental (I have commercial and medical).  All that pushes to find fuel on the road which in turn means AvGas.  I forgot to mention, I have a 750STOL so I'm not complaining about speed or range.  I just don't want to damage a really nice engine.  Again, thanks for the timely and much appreciated response.


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