What fuel for a Rotax

[Stan]

I am somewhat confused about what fuel to use for a Rotax 914T and 912 S. I was told to only use regular unleaded petrol and now I hear that AVGAS is also OK. Any comments from the boffins. My department is getting two YUMA's and I am trying to sort out fuel for them through the gov. purchase system. The guys going near Rand Airport may have seen one of them flying around there.

[Mogas]

Stan
Rotax does not recommend the use of leaded fuel. You can use low lead (blue) avgas but it will shorten the time between oil changes.
The 912/914 engines are modern high compression engines with hardened valve seats.
Older technology aviation engines use lower compressions and have softer valve seats. This technology demands the use of leaded fuel to prevent detonation and lubricate the valve seats.
The attachment is about the recomended oil, coolant and fuel for your Rotax.

[Stan]

Thanks