Recognize that this is marketing. This motor one-ups all the other motors in the world with this claim. The only problem is that for some mysterious reason, it suffers from chronic head gasket failure. How completely unexpected. I took this quote from Wikipedia:
One notable feature, advertised at the time, was the "limp home" fail-safe mode which allowed the engine to continue running for a limited time without any coolant. Supplying fuel to only one cylinder bank in turn, the engine would "air cool" the inactive bank. This technique, combined with its all-aluminum construction and large oil capacity, allows the engine to maintain safe temperatures, allowing a Northstar-equipped car to be driven with no coolant for about 100 mi (161 km) without damage.
I remember a commercial with the new Seville driving through the Sahara without a drop of coolant, but I couldn’t find it online. I can tell you that by the end of that drive in the Sahara, that Seville needed to have its head gaskets replaced, and its cylinder head bolts time-serted. The owner probably didn't know it for a few months though. This solution does an adequate job of keeping oil temperatures low enough to operate the lifters, but it ignores the fact that the aluminum head expands far sooner and much more than the steel bolts that attach it to the block. This expansion creates thousands of pounds of force under the heads of the bolts and increases the clamping load exerted on the threads massively. Think of it as turning the cylinder head bolts another 180 degrees. Thermal expansion is a bitch. No problem though, you don't have to worry about catastrophic failure, because the cylinder block is made from soft aluminum, and the threads just yield a little. When your heads cool, the head gaskets expand to make up for the difference, and you're fine. The problem is that the thread was compromised and it is already hastening the failure of your head gaskets, because their clamping force was decreased. And my experience is that these motors are overheated alot. Also, their water pump is driven by the camshaft, which means that its imminent failure doesn't conflict with all the engine driven accessories. Your battery light doesn't come on, your power steering still works, hell, even your air conditioning works. On almost every other car in the world, blowing a water pump or its drive belt results in loss of power steering, and charging which panics people and causes them to pull over. Cadillac drivers typically still finish running their errands, driving to work, or whatever they were doing before they call to make an appointment to get the car checked. And why not? This is Cleveland, not the Sahara. If it can go 100 miles in the Sahara (it may have been 50 in that particular commercial), then driving it 12 miles in Cleveland should certainly be fine. People may not realize this, but these are very thermally challenged motors; one day their water pump will fail, a few weeks later the rubber disc will blow out of their thermostat and restrict the coolant flow to a point where the engine always runs at at least 240 degrees, then about six months later, the radiator petcock will randomly break off and fall out while sitting at a red light, then if you forgot to wash the back of your motor after winter, the heater transfer pipes will rust a hole in them, and empty the cooling system. Once that's all fixed, the coolant reservoir will spring a crack. Radiators and hoses fail at a pretty good rate as well. None of these failures are critical, and most of their repairs are inexpensive, but everybody remembers that this car can go 100 miles without coolant and keeps on going. I mean c'mon, coolant is merely a luxury for this car. BMW owners, with the exception of the guy in my previous post, know that if they drive their car without coolant, they will be paying somebody at least 8 grand to fix their engine, so they pull over and call a tow truck. Plus, they are reminded that something bad has happened, because even if they ignore the silly lights and gauges, their steering wheel is impossible to turn. I recently learned that if you overheat a BMW over and over and over again, the force of the expanding aluminum head will pull the head bolt threads out of the block. I believe that the same applies to the Northstar. If you don't want to pay somebody like me three-quarters the book value of your car to fix your head gaskets and bolt threads, there is a very simple thing you can do: pull off the road before the car overheats, and call a tow truck. Treat the “limp home” fail-safe mode as a last resort, and know that driving that extra few miles will likely cost you thousands. AAA costs about $50 per year. Believe me, it is a worthwhile investment if you own a vehicle with a Northstar. Now you can cross "head gasket failure" off your worry list, and focus all your attention on worrying about your half-case seal, which will definitely fail.