Mineral oil degrades very quickly and loses its lubrication and heat dissipation properties, whereas synthetic lasts much longer without degrading... ideal in a situation where long service intervals are likely, and more extreme operating environments.
There's a lot of mis-information about oils. For example, my TM engine is made by Kubota
Kubota themselves say you should use mineral oil...... Blueline say you should use fully synthetic in the engine........ But Alltec's service engineer says you should use part-synthetic.
So who the F are you supposed to believe??!!!