I have a collection of Stihl power equipment, some from deceased family members.
4 chainsaws: 011, MS180C, MS250, MS290 Farm Boss
3 trimmers: FS55, FS65, FS90
+The FS90 has a 4-stoke engine, but with no oil sump
2 blowers: BG55 and BG56
I use 89 octane fuel (per Mfr) with ethanol, Stihl...