These are aluminum blocks and don't withstand overheating very well.
I agree with this 100%. If you see ANY signs of it overheating, pull over, stop the engine, and let it cool down. In matter of fact, I changed something out and needed to refill my coolant one day. Drove it less than 5 mins, hit the highway and had to pull over due to overheating. I had AAA tow me back home, less than 1 mile away. With that said, I am very cautious about any vehicle with aluminum heads as they can quickly heat up and cool down. Heating up is the issue and can cause internal damage.
If you have it at home, do a compression test to make sure your getting compression on all cylinders. If you don't have compression, then you'll need to investigate deeper or have someone do it for you.
BTW... oil in the intake manifold is quite common, which sucks. You'll eventually need to walnut blast your intake valves to clean them.