90 octane in ROTAX?

[FastEddieB]

On our way to or from Sun 'n' Fun, Karen and I were planning on stopping at Winter Haven (KGIF), since they have MOGAS.

I just called, and what they have is 90 octane, ethanol-free MOGAS. The fellow there said "all the ROTAX guys" use it.

IIRC, ROTAX specifies 91 octane or better, and most of the high test around here in GA is 93 octane.

Would a tank of fresh 90 octane be an issue? Especially if being mixed with higher octane already in the tanks and/or 100LL down the road?

Just wonderin'!

[roger lee]

Hi Eddie,


Start with some 100LL on the first leg.
It would be better if you started with the 100LL and then added the 90 later. That said it shouldn't make a difference. You could even add a little octane booster for that little bit. People let there fuel set for long periods then run the engine. I guarantee the octane has degraded down to 90 for them and they run it.

[FastEddieB]

Start with some 100LL on the first leg.

Well, the plan is to leave the GA mountains full of 93 octane MOGAS, then top off with the same at Cordele, GA (thanks to a friend).

If I do get any at Winter Haven, it would just be enough (5 to 10 gals) to arrive at LAL without minumum fuel (after a 3 hour leg starting from Cordele with my 18 gal max).

Thanks for the input - I'm sure the mix would still be above 91 octane combined.