Will diesl oil damage a Chevy block?

Answer 1

As in...

1. spilled some on the engine?
2. poured some in the crankcase?
3. filled the fuel tank?
4. used it as an engine coolant in the radiator?

Answer

1. If you spilled some on the engine... don't worry. No harm done.
2. If you poured some in the crankcase, just drain it out, replace the oil then change the oil again in about 100 miles. The diesel fuel will soften deposits and tend to cause the next oil to get dirty very fast. Some people have even put one quart of diesel fuel in the crankcase before changing the oil, just to get rid of deposits, although I don't recommend it.
   
3. If you filled the tank, just siphon as much out as you can and fill it with gasoline. It will run a little rough for a while, and you may need to start it with the assistance of some starting fluid, but the engine will eventually burn out all of the residual diesel fuel and it will be okay. It may take a couple tanks to clear it all out though.
4. If you used it as an engine coolant in the radiator, just drain and flush the coolant a couple times. I don't mean to flush with chemicals, just run some water through it. A small amount of light oil in the coolant won't hurt anything.