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I guess the bottom line is what oils seem to work best for our cars under more extreme circumstances. I can't include sub zero temps as I have very little experience of this sort of climate. So for us, stop-start traffic is bad but of course running on the track is by far the hardest condition for a car, any car.

As someone has mentioned, 99% of us run wet sumps. I have a dry sump in the race car but I'm not including this in the discussion. As oil gets hotter, it gets thinner. Even the Race 25w/60 we run on the track is pretty much like hot water in terms of it's viscosity after some laps. Running 10w/40 or lower visc is basically suicide under these conditions. If 25w/60 is watery when hot, a 10w/40 or worse, 0w/30 is more like vapour when hot. Essentially you have lots of spinning metal parts working within very tight tolerances and all they really 'want' to do is smash the crap out of each other (technically speaking!). The only hope you have in those extremely sudden and brief moments where you might have some oil starvation to the big end bearings is for the oil film strength to provide the last bastion of protection and save you from spinning a bearing...or worse. We have read of many people who have spun a bearing or worse and more often than not they are using a lower visc synthetic oil.

I agree that you need to change your oil regularly and utmost in protection is making sure you have sufficient oil cooling for your circumstances. Comparing a car on a track to a street car isn't entirely valid, granted. But I will sacrifice a couple of hp and this supposed cold start wear due to running say a 20w/50 dino oil, for peace of mind both on and off the track. Sure, if you live in parts of Europe and North America, then the Winters can demand a lower weight oil than I run...but then again, many of you guys don't even drive your 944s in Winter anyway. You've all got those big ass Trucks!! :-)