oil viscosity

[jorrow]

I have always heard to use 60w oil in old bikes especially here in texas where we see 90 -100 degree weather all summer long, however I have often questioned the need for such heavy oil. If you convert Harleys original "heavy use oil" you actually are closer to a straight 50w. Could it be the old" bigger is better" philosophy in action , or do these old machines really need the oil that heavy. I would imagine that starting these engines cold with straight 60 is a bit hard on the rods, cases, etc...Remember, thinner oil cools better, thicker oild holds its viscosity longer. I'm sure there are plenty of good opinions out there, and I would love to here from you. And...what of multiviscosity oil? A factory engineer at the daytona exhibition told me that 20w-50 would actually be excellent for the old bikes and would actually thicken up past its 50w margin....any opinions???, or bad experiences???