92 octane will do no harm but provide nothing in return either. Avoid anything higher, though! I ran a tank of 115 race gas through my Toro years ago to cut my super-small lawn (30 minutes max). After 20 minutes, the engine had no power and sounded like I’d burned an exhaust valve. The race gas had heated the exhaust valve so much it wouldn’t close. The valve clearance had been completely closed up, and then some! It ran fine once it had the time to fully cool off. No more race gas in the mower!