The 87 is fine. Depending on how you work the engine the Stihl that Bill provided would be ok. If you run them hard with a lot of hovering and torque rolling with minimal cooling you want to switch over to Stihl Ultra. It's a better product and does not stick rings as easily as the other. Not that either are noted for sticking rings, but the Ultra is definately the better oil. Don't ask, I can't tell you....

50-1 with either one is just fine.