If you're using 0W-Anything oil, you might want to read this...
 

I know I've seen several posts indicating that some members are using 0W-oils in their engines. While it's your engine and your choice, I thought you might be interested in this article:

Plain Bearing Lubrication

Pay particular attention to the Stribeck loading/speed curves for loading/RPM/viscosity thresholds. For an even lightly loaded bearing (like in a Toyota), their minimum recommendation is ISO 32 or 46. For those of you that don't remember, this equates to an SAE "made-up" viscosity number of 10W or 10, at a minimum. I know it's just an opinion, but they are lubrication professionals, and they only have science to support their opinion, not Dura-Lube infomercials. Too bad for them, eh?

In a related question, has anyone you know tried to retrofit the split roller bearings onto an SBC crank?

http://www.machinerylubrication.com/...dler_fig_1.jpg

I'm thinking they could support some serious RPM with very low frictional losses. They would be heavy, though. It really wouldn't matter much on the crank journals, however.

Just checking.

Good stuff. No idea on the roller bearings in a SBC here.....

the info was informative.. but not solely applicable to zero
 

it could apply to almost anything that even used thicker oils. As zero anything goes.. I would only consider M1. The specs previously available (which might no longer be valid since mobil has changed hands and it is said that the manufacture of M1 has undergone cost cutting) for Zero-30 were better than the 5-30 version of mobil 1.

informative..
reminds me why oil coolers and the proper oil is a must on hi output engines..