expansion tank fluid level

The Overflow Bottles are Not part of the engine package and are often supplied by the airframe manufacturer.

Is your bottle an Official Rotax Bottle with the Word "Rotax" molded into the plastic or something more generic?

Hello Bill,

I havent look't close enough to determine that, next time i have the cowling off, i'll take a look.  

b-well / jg 

you can judge the correct level that required is after 50C ground run. after reaching 50 C oil temp, if fluid level is still down from marked level (mentioned on Bottle) re-fill it with proper liquid.

newly re-filled radiator causes level low due to some bubble inside water passages of engine block , water pump etc.