So basically, if I go with a 0w-30 I will get the same protection when the engine
warms up as I would with the 5w-30? Also, if I use 5w-20 then I will see no difference and could possible still get the noise on cold start?
The problem with the 0W-XX is that a any motor is designed for a specivic viscosity. If you use to thin of an oil in a very high mileage motor, it will just get burnt. (Example: A seventies Chevy
350, 250K miles, never been rebuilt -> it would go thru a 0W-XX oil like a football player through water on a hot summer day)
The problem is mainly the cylinder to piston clearance. If the bore gets larger, and the surface has a couple of scars from wear, oil is more likely to pass by the rings and it gets burnt. The larger the clearances in a motor are, the higher voscosity you want to use.
Keep in mind that using a lower viscosity oil does not eliminate the problem, it just reduces the time for the oil to get through the passages.
One very important number, which has not been mentionned in this thrad before is the pour point. It tells you how cold oil has to be, to not be pourable any more - the lower, the better.
Get your own oppinion and ave a look at this sheet: