<VV> y'all

[HallGrenn at aol.com]

In a message dated 6/27/2005 3:59:43 PM Eastern Daylight Time, pp2 at 6007.us 
writes:

> If I had 
> trouble in hot weather, I would try a straight 30 racing oil before 
> anything with such a range of weights. If overheating or losing oil 
> pressure on that I would want to find out why.
> 

Maybe the oil companies are doing things differently now, but when I cared 
about this stuff ten years (or more) back I researched the specs.  (mostly 
Quaker State and SAE).  The multigrades didn't have different weights.  As someone 
else said, the oil manufacturer added long chain polymers so that as the oil 
reached operating temperature it wasn't any thinner that the target viscosity.  
So a 10W-30 wasn't any thinner than a 30 weight at operating temperatures.  
The problem is that shearing and other wear factors "cut up" the long chain 
polymers and you didn't keep the higher viscosity as time went on.  I know there 
were other qualifications, but the primary target was viscosity and wear 
characteristics at operating temperature so you could have a year round oil.

Bob Hall