The best fuel to use for the MS 291 is the STIHL Ultra 2-cycle engine oil which is the fuel that will provide you with maximum performance as well as extend your engine lifespan. However, you will be fine as long as you use a high-octane and low ethanol fuel by STIHL with an ethanol level lower than 10%. As per the bar and chain oil, a good choice would be the platinum bar and chain oil by STIHL.