I don't know which type of coolant he used as he won't say.
But the place where he lives gets the water supply from ground water which is notorious for being full of all kinds of mineral salts. I am suspicious of this.
The parts do look like the ones I used but you are correct in thinking there seems something fishy going on.
He said he removed the thermostat first and it was jammed up with crud so then he took off the pump and it was the same but then he said he decided to take off the heads to see if I put the gaskets on wrong blocking the water holes.
I think that was weird. Not the first thing I'd think of doing on a engine that has done 10 hrs of running without overheating. If you put the gaskets on wrong and blocked the water holes the motor would cook in two minutes not run for 10 hrs. Strange bit of thinking.
I'm wondering if I'm going to see a parts sale on ebay?
Following a demand for a refund.
I also find it weird he took nearly a year to tell me all this when it supposedly took place a week after receiving the engine.