step father did the gas oil fill swap, froze that 14hp briggs real quick, to the point that i could not save it. crank shaft wasted, cylinder scored what a mess.
So along the same lines. I was rushing one day (10 yrs with saw/cutting) and took both caps off saw in rush to fill - bar oil and fuel. Filled both up - with opposite cans. Put caps on. Walked down driveway - choked and pulled starter cable as I have 1000 times and nothing - pulled 2x - nothing. then had lightbulb moment and thought wtf - think I messed up. Took caps off and sure enough I did. So moral of my story although not totally relevant - is to shake it off. TBH didn't read whole thread but just another perspective