Never heard that before. The UOA's all measure the percentage of insoluble material (which is a measure of oil filtration). Otherwise, UOA's are the best way to determine how YOUR ENGINE is getting along with the oil you put in it.
My previous car was a 2007 Altima 3.5SE VQ35DE. I abused the crap out of that car and had it for 40,000 miles before trading. I have documented UOA's for nearly every oil change I performed on that car using Castrol Syntec 0W-30 (aka, German Castrol, aka, G.C.).
That is the ONLY oil I've used since the UOA's for the Altima were as perfect as you could ask for. Now the UOA's on the Z (of which there are only 2 so far) are still trending down on the wear metals, but look absolutely perfect considering miles and driving conditions.
The 0W-30 flows like a 0W oil at 32ºF. And basically, that's the only time you really care about the 0W. The only reason I use 0W is because the 0W-30 is a German engineered and produced oil. All other viscosities of Castrol Syntec are designed differently and aren't any better than Mobil1. The G.C. actually holds its viscosity better than nearly any other 30W oil at high temps, so that's all I have ever used and all I ever will use. Plus, it's not terribly expensive ($6.50/qt) and is accessible (available at all Autozones).
Late,
Trav
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