It won't run hot if you have a cooling system that works. Run synthetic oil if your worried about hot oil. My preferance is ROK Block block filler. Then Moroso. The Rok block is more like an epoxy, and mixes more soupy. This allows it to flow very well into all the voids all on its own, no help needed, like with the concrete sometimes needs. The other beauty of the Rok block, is it sets in about half hour, so, you can do the otherside right away, no waiting over night, so, in the shop setting, its a time saver.
Just follow the direction, yes, its supposed to be pretty soupy. If you mix it thicker, more like regular block filler consistncy, it will set before you get it all in, then you could have issues. Kinda like if you mix to much activator into bondo, it hardens really quick. It gets hot like that too.
Frank