I have to agree wit GRINGO Flyer here.

In my shop I have many types of engines Webra, Thunder Tiger, Super Tiger, and yes OS. IF you take care of the engine it will last 10 -20 years.

The key to happy engines is knowing how to tune them, use the right fuel and don't try to get 20,000 rpm out of an engine designed to run at 13,000 rpm. BTW - I also beleive in Caster Oil vs Synthetic oil.

IMHO it has a much better ability to lubricate and dissipate heat.