What the hell are you talking about? What high heat does a lubricant need to stand up to with a firearm? The only part I know of that gets really hot is the bore of the rifle... and you sure should not be putting motor oil in it before each shot ...
I am still going to recommend G-96 Gun Treatment. It is silicone based and does not gum up with age, it does not attract and hold dust and dirt, it also does not become stiff at 60 degrees below zero.
I don't think that can be said of your motor oils.
I have never seen a product that doesnt gum up and turn to crud. I have used G96 and was not happy with the results. I have tried oils from engine oil to lubricants that go for hundreds of bucks a litre. It all goes south - some sooner than later.
I usually only clean my pistol these days after it really needs it - every four to five thousand rounds. So I clean every two to three weeks or so. Vygur is a new ipsc shooter and is looking for something readily available and cheap. Engine oil is the way to go.
I dont know about anyone else but my pistol heats up like a mother after a few hundred rounds or so in a practise session.
Every lubricant gathers dust and turns into paste. I moved away from the NWT to get away from minus 60 but if anyone wants to shoot in a cold climate - go ahead.
There is no magic lube. Buy the cheap stuff and wipe off/re-apply often.