Castor oil doesn't create friction. It's a lubricant. It *reduces* friction. Also, when castor oil breaks down, it turns into *even better* lubricants.

Yes, it's thicker than synthetic oil, so it could produce some fluid drag, but again I only used a very small amount.

There is no other explanation that accounts for reduced operating temperatures in *all* of my engines in the middle of the summer. The engines are obviously being lubricated better with the extra oil in the fuel.