We have used k100 for years with no problems or ill effects . Alcohol runs cooler than gasoline and diesel. That's why alcohol fueled drag cars use it, so they can run higher compression. High octane gasoline is actually slower burning and burns colder than low octane gas. Diesels already run high compression. And run on compression for ignition unlike a gas engine that uses spark for ignition. I suspect your friend had other issues going on with his tractor or he was pouring gallons of the stuff in his tank instead of draining the tank of contaminated fuel like he should have. I'm guessing since you say the engine seized that he diluted the fuel so much, (especially with this crap we have to run now ) that he had no lubrication and locked it up. If it would have ran hot like putting gasoline in a diesel, it would have caused extremely high unstable cylinder pressures and shattered pistons or thrown rods through the block. In winter when they blend diesel so it doesn't gel up, it burns colder than straight number 2. Us diesel drivers dread the day they switch fuel at the pumps because we lose power and fuel milage.